The researchers surveyed peer-reviewed literature published through mid-2024, searching PubMed, Google Scholar, ScienceDirect and Wiley Online Library for studies combining cannabidiol with terms covering sunscreens, antioxidants, inflammation, UV radiation and skin biology. From that search, 19 studies made the final cut: four review articles, nine in vitro experiments, three animal studies, one human clinical trial and two mixed-method investigations. The authors are candid about the limits of their approach. Because this was a narrative review rather than a systematic one, they did not apply PRISMA methodology or formal risk-of-bias assessment, and they acknowledge the search may have missed relevant work, particularly non-English publications.

The most striking findings concern CBD’s antioxidant chemistry. Structurally, the molecule shares features with vitamins E and C: phenolic hydroxyl groups attached to aromatic rings that can donate hydrogen atoms to reactive oxygen species and free radicals, interrupting the chain reactions that damage lipids, proteins and DNA. CBD is also highly lipophilic, allowing it to accumulate in cell membranes and stabilize them in a manner reminiscent of vitamin E. In rat experiments, chronic UVA and UVB exposure distorted keratinocyte membrane phospholipid metabolism, and topical CBD partially reversed those changes, downregulating harmful lysophosphatidylcholines and phospholipase A2 activity while upregulating protective phosphatidylethanolamines and phosphatidylserines. In human keratinocytes stressed with hydrogen peroxide or UVB, CBD reduced malondialdehyde and 4-hydroxynonenal, two well-established markers of lipid peroxidation, and modulated proteostasis networks governing protein folding and redox balance in ways that increased cell survival.

Beyond these direct chemical effects, CBD appears to manipulate the skin’s own antioxidant machinery. The review highlights its interaction with Nrf2, a redox-sensitive transcription factor often described as the master regulator of cytoprotective gene expression. Under normal conditions Nrf2 is held inactive by its nemesis Keap1, which tags it for destruction by the proteasome. Oxidative stress disrupts this pairing, freeing Nrf2 to enter the nucleus and switch on genes encoding superoxide dismutase, glutathione peroxidase and heme oxygenase 1. Intriguingly, keratinocyte studies suggest CBD is only a weak Nrf2 activator but a strong inhibitor of BACH1, a transcriptional repressor that works alongside Nrf2 to control heme oxygenase 1. This positions CBD as an Nrf2-independent booster of HMOX1 expression, encouraging keratinocyte differentiation and cytokeratin production, processes critical to maintaining a skin barrier that resists UV-induced DNA damage.

The anti-inflammatory story runs through a different set of molecular switches. CBD appears to be a major inhibitor of NFκB signaling, the central hub of the inflammatory response. Normally locked in the cytoplasm by its inhibitor IκB, NFκB is released when pro-inflammatory signals such as tumor necrosis factor alpha trigger IκB’s degradation, allowing the transcription factor to activate genes for cytokines, chemokines and adhesion molecules. UV irradiation drives inflammation through exactly this pathway, and in three-dimensional human keratinocyte cultures CBD counteracted it, restoring IκB levels and suppressing NFκB. CBD also dampened the NLRP3 inflammasome and the pro-inflammatory protein PGAM5, while full-spectrum CBD extract showed high-affinity inhibition of NLRP3 and TGF-β1 responses. In human skin fibroblasts, CBD elevated PPARγ, a nuclear receptor that represses inflammatory pathways, and in an acne study it significantly suppressed TNF-α, IL-1β and IL-6 in human sebocytes.

The endocannabinoid system adds yet another layer. CB2 receptors, found in immune and peripheral tissues including skin, can restrain pro-inflammatory cytokine release, and CBD’s modulation of CB2, along with its desensitization of TRPV1 channels activated by oxidative stress and its activation of adenosine A2A receptors, may collectively calm overactive immune responses in UV-damaged skin. One study of patients with psoriasis, atopic dermatitis and scarring found that a CBD-enriched ointment improved disease severity, quality of life, skin hydration and elasticity with no adverse effects. The review also flags a fascinating effect on melanocytes: CBD can activate p38 and p42/44 MAPK signaling and independently upregulate MITF, tyrosinase and related proteins, enhancing melanogenesis, the production of the pigment that naturally scatters and absorbs UV radiation. This raises potential applications for hypopigmented disorders and hints at melanin-mediated photoprotection.

But here is where the enthusiasm must be tempered, and the review is refreshingly blunt about it. Spectral analyses show that CBD absorbs UV light predominantly between roughly 220 and 280 nanometers, a range overlapping UVC, which is filtered out by the atmosphere, and only minimally touching the UVB band that sunscreens must block. In one comparative study, CBD showed the strongest cytoprotection against UVA-associated injury while cannabinol performed best against UVB, but neither CBD nor its relatives demonstrated direct photoprotective absorption at the wavelengths that matter. The authors emphasize that the observed cytoprotective effects should not be interpreted as sunscreen activity. CBD’s benefits, if real, would be indirect, working beneath the filter layer to help skin cells survive whatever radiation gets through.

Safety questions also complicate the picture. Most systematic safety data come from oral CBD, where randomized trials have identified increased risks of diarrhea, somnolence, decreased appetite and abnormal liver function tests, though the hepatic and sedation signals were concentrated in high-dose childhood epilepsy studies using drugs like clobazam and valproate. CBD is metabolized by CYP450 liver enzymes and can be a potent dose-dependent inhibitor of their activity, a concern that depends heavily on how much of a topical dose actually reaches the bloodstream. Evidence on that front is mixed: in a 17-day study of 46 healthy adults, CBD was detectable in blood after repeated use of three of five commercial topical products, though concentrations were far below those from oral or inhaled use and no cognitive or physiological effects appeared. Topical tolerability data remain thin and formulation-dependent, with patch-testing studies showing selected CBD products were non-irritating and non-sensitizing in healthy adults, while a transdermal gel trial saw application-site dryness, pain and one case of irritant contact dermatitis.

There is one tantalizing human data point. A small pilot randomized trial of nanoparticle-encapsulated topical CBD, involving just 19 participants, found less erythema on treated skin after UVA irradiation, along with reductions in epidermal hyperplasia and cellular stress and aging markers. But the study measured no SPF and included no active sunscreen comparator, so it cannot speak to whether CBD would add anything to a real product. The review also raises a subtle photochemical concern: when CBD oxidizes, it can form the cannabinoid quinone HU-331, which absorbs UV near 270 and 409 nanometers and has shown topoisomerase-II inhibition and endothelial-cell apoptosis induction in non-skin experimental systems. CBD and its hydroxyquinone have also generated reactive oxygen species during mouse liver microsomal metabolism. None of this demonstrates phototoxicity in human skin, but it marks genuine toxicologic uncertainties that demand study before CBD rides around in a sun-exposed bottle.

The regulatory landscape adds a final layer of complexity. In the United States, sunscreens are regulated as over-the-counter drugs, and only zinc oxide and titanium dioxide currently meet the FDA’s Generally Recognized as Safe and Effective standard, while the 2022 Modernization of Cosmetics Regulation Act has tightened scrutiny of cosmetic ingredients, with new 2026 legislation targeting full-spectrum CBD products specifically. Any manufacturer hoping to add CBD to a sunscreen would face registration, human safety substantiation and adverse event surveillance requirements. The review’s bottom line is measured: CBD may eventually earn a role as an adjunctive, non-filter component of photoprotective skincare, but the evidence base, dominated by in vitro and rodent work with enormous variability in models and doses, is nowhere near supporting claims of sun protection. Until standardized SPF, stability, photostability and human safety testing say otherwise, your sunscreen’s active ingredients should remain the ones with proven track records.

Subject of Research: Preclinical evidence on cannabidiol's effects against ultraviolet-induced skin damage and its potential as a sunscreen additive

Article Title: Cannabidiol and ultraviolet-induced skin damage: a narrative review of preclinical evidence and translational considerations for sunscreen additive development

Article References: Papadeas, G. G., Szeto, M. D., Reed, M. J., Paul, A., Runion, T. M., Anderson, J., & Dellavalle, R. P. (2026). Cannabidiol and ultraviolet-induced skin damage: a narrative review of preclinical evidence and translational considerations for sunscreen additive development. Archives of Dermatological Research, 318(1), Article 430. https://doi.org/10.1007/s00403-026-04888-x

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04888-x

Keywords: cannabidiol, CBD, sunscreen, UV radiation, photoprotection, skin cancer, antioxidant, anti-inflammatory, keratinocytes, melanocytes, Nrf2, dermatology

The problem the researchers set out to solve is a genuine paradox at the heart of modern photoprotection. Organic UV filters in sunscreens have faced mounting scrutiny over skin irritation, systemic absorption into the bloodstream, and potential endocrine-disrupting properties. Inorganic filters such as titanium dioxide and zinc oxide avoid some of those concerns, but when formulated at the nanoscale to improve cosmetic transparency, they become photocatalytically active under UV light. Upon irradiation, they generate highly damaging reactive oxygen species, including hydroxyl radicals and superoxide anions. In other words, the very materials deployed to prevent UV damage can themselves contribute to the oxidative stress they are meant to mitigate.

Cerium oxide, or ceria, has long been viewed as a compelling escape from this trap because of its dual-action mechanism. It absorbs broadly across both UVA, spanning 315 to 400 nanometers, and UVB, spanning 280 to 315 nanometers, providing a physical shield against solar radiation. At the same time, it acts as a regenerative catalytic antioxidant, cycling reversibly between its Ce3+ and Ce4+ oxidation states to neutralize reactive oxygen species. Yet ceria is not perfect either, since it can exhibit some photocatalytic activity of its own. The research team, led by Rajib Chandra Das and Konstantin Konstantinov at the University of Wollongong, hypothesized that ceria’s full potential would be realized not as a standalone agent but within a rationally designed heterostructure, where a minimal amount of highly active ceria is anchored to a stable support.

The synthesis itself is elegantly simple, which matters for scalability. The researchers prepared yttrium oxide nanoparticles by precipitating yttrium nitrate with ammonium hydroxide, washing and annealing the product at 500 degrees Celsius. They then dispersed these host particles in water, added a small quantity of cerium nitrate, and triggered the in-situ precipitation of ceria quantum dots directly onto the yttria surfaces using ammonium hydroxide and hydrogen peroxide. The resulting nanocomposite contained just 10.93 weight percent cerium, present exclusively in quantum dot form, with the remainder being the yttria host.

Physicochemical characterization confirmed the design worked as intended. Transmission electron microscopy revealed near-spherical ceria quantum dots averaging 5.8 nanometers in diameter, uniformly distributed on the larger, irregularly shaped yttria particles. High-resolution imaging showed clear lattice fringes with a spacing of 0.267 nanometers corresponding to the (200) plane of ceria, confirming the dots remained highly crystalline. Crucially, the surface anchoring prevented the aggregation that plagues free nanoparticles, maintaining a high functional surface area of accessible active sites.

The most striking findings emerged from the analysis of the interface between the two oxides. Rietveld refinement of X-ray diffraction data revealed that lattice microstrain in the nanocomposite reached 1.33 x 10^-3, higher than that of either pure component, indicating significant structural distortion where the two crystal lattices meet. X-ray photoelectron spectroscopy then showed that the relative concentration of redox-active Ce3+ more than doubled, rising from 16.5 percent in pure ceria to 35.9 percent in the nanocomposite, accompanied by an oxygen vacancy concentration of 39.0 percent. Because each oxygen vacancy formed reduces two neighboring Ce4+ ions to Ce3+ to preserve charge balance, this defect-rich environment provides a direct chemical basis for enhanced antioxidant capacity. The strained, defect-laden heterointerface appears to structurally stabilize the redox-active sites that do the scavenging work.

Optical measurements added further evidence that the two phases form a genuinely coupled electronic system rather than a simple physical mixture. Pure ceria absorbs strongly across the UV region with a band gap of 3.15 electron volts, while yttria is largely transparent with a wide 5.20 electron volt gap. The nanocomposite showed an apparent band gap of 4.93 electron volts, an enormous blue shift of 1.78 electron volts relative to the ceria phase. A shift of that magnitude cannot be explained by mixing or quantum confinement alone and points to a functional heterojunction in which the electronic structure of the quantum dots has been profoundly altered by their intimate contact with the host.

Functional testing confirmed the practical payoff. In acellular assays using crystal violet dye as an indicator, none of the materials showed significant photocatalytic activity of their own, an important safety attribute. But when a strong ROS-generating photocatalyst was introduced, the nanocomposite delivered exceptional protection, reducing the dye degradation rate constant nearly six-fold compared to the control, outperforming both pure yttria and pure ceria. In human HaCaT keratinocyte cells, the nanocomposite mitigated the inherent cytotoxicity of the yttria host and, remarkably, produced a pro-survival effect under normal conditions, increasing long-term clonogenic survival even before any UV exposure. After UV irradiation, cells pretreated with the nanocomposite showed more than a threefold increase in clonogenic survival compared to untreated controls, with a protection enhancement ratio of 3.46 after the harshest 15-minute exposure. Pure ceria performed slightly better, but the nanocomposite achieved this with barely a tenth of the cerium content.

The authors attribute the nanocomposite’s performance to a synergy of four factors: enhanced redox reactivity from the defect-rich interface, maintained nanoscale dispersion of the quantum dots, suppression of unwanted photocatalysis, and a biocompatible surface layer that masks the toxicity of the underlying host. They also note a clear path for improvement, suggesting that replacing yttria with a more inert and biocompatible host could push performance even closer to that of pure ceria. As a blueprint for next-generation photoprotective materials, the study makes a persuasive case that interfacial engineering, rather than simply loading more active ingredient, is the key to sun protection that works with biology instead of against it.

Subject of Research: Ceria quantum dot-yttria oxide nanocomposites for UV photoprotection and reactive oxygen species scavenging

Article Title: Nanoarchitectonics with solid state surface dispersion of ceria quantum dots on nano-yttria for efficient photoprotection

Article References: Das, R. C., Dewanjee, S., Chaki Borrás, M. L., Sluyter, R., Lerch, M., & Konstantinov, K. (2026). Nanoarchitectonics with solid state surface dispersion of ceria quantum dots on nano-yttria for efficient photoprotection. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13848-9

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13848-9

Keywords: ceria quantum dots, yttrium oxide, nanocomposite, photoprotection, UV radiation, reactive oxygen species, antioxidant, heterostructure, skin cells, keratinocytes, nanoarchitectonics, oxygen vacancies

The stakes are considerable. Non-melanoma skin cancer, comprising basal cell carcinoma and squamous cell carcinoma, ranks as the fifth most common cancer globally, with roughly 1.2 million new cases and 69,000 deaths estimated in 2022. Australia leads the world in age-standardized incidence at 140.1 cases per 100,000 inhabitants, while the absolute burden of cases concentrates in Northern America and Europe. Melanoma, though less frequent and ranking 17th among incident cancers, remains one of the most aggressive malignancies, arising from melanocytes and marked by a heightened capacity for invasion and metastasis. Notably, recent global estimates indicate that absolute deaths from non-melanoma skin cancer now exceed those from melanoma, at approximately 63,000 versus 57,000 worldwide, a trend that underscores the often-underestimated burden of these tumors and their more aggressive subtypes.

The review’s central hypothesis links sleep and circadian health to skin cancer defense. Melatonin synthesis is strictly governed by the suprachiasmatic nucleus, the master circadian clock, which lifts its inhibition of the pineal gland only after dusk. When sleep is disrupted or artificial light floods the night, melatonin production falls, and with it a cascade of cutaneous protections. The authors argue that this circadian-regulated hormone acts as a physiological safeguard for the skin, and that its decline, commonly seen in people with sleep disorders and in the elderly, may impair immune surveillance and facilitate tumor progression. Epidemiological and experimental evidence supports the broader premise: simulated night shifts in humans disrupted the rhythmic expression of DNA repair genes and increased sensitivity to DNA damage, while clock proteins such as CLOCK, BMAL1, PER, and CRY have been shown to coordinate DNA repair, cell cycle control, and programmed cell death.

The molecular detail is where the review becomes particularly compelling. In human keratinocytes, melatonin and its metabolites acted on the earliest consequences of UVB irradiation, countering oxidative and nitrosative stress, shoring up antioxidant defenses, and reducing the formation of DNA photoproducts, with increased phosphorylation of the tumor suppressor p53 supporting a role in DNA damage signaling and repair. In melanocytes, protection ran through the NRF2 pathway: melatonin boosted expression of this master antioxidant regulator, and when researchers silenced NRF2, the hormone’s defensive effect against UVB-induced oxidative damage largely vanished. Mouse studies add a striking temporal dimension. When animals were chronically exposed to UVB at a time of low DNA repair activity, they developed skin tumors earlier and harbored more invasive squamous cell carcinomas than mice exposed at a time of high repair capacity. Human skin, too, shows time-of-day variation in UVB-induced erythema and p53 activation.

Beyond DNA repair, melatonin appears to interfere with the signaling cascades that keep cancer cells alive and proliferating. In B16F10 melanoma cells, the hormone combined with endoplasmic reticulum stress to reduce cell survival through interference with the PI3K/Akt/mTOR pathway, a central growth-signaling axis. Melatonin also reshapes mitochondrial function, reducing oxidative phosphorylation, ATP production, and mitochondrial membrane potential while amplifying reactive oxygen species and proton leak, metabolic shifts that can push cells toward intrinsic apoptosis. Intriguingly, when paired with BRAF and MEK inhibitors, the standard targeted therapies for BRAF-mutated melanoma, melatonin may enhance treatment efficacy by suppressing MAPK signaling and promoting mitochondria-mediated cell death. The hormone also modulates pigmentation, with its metabolite 5-methoxytryptamine enhancing tyrosinase activity and melanogenesis in melanoma cells, a response thought to provide a physical shield against ultraviolet radiation.

The evidence, however, is not uniformly encouraging, and the review is candid about the caveats. Melatonin’s actions are strongly dose-dependent and context-dependent. At physiological concentrations, the hormone is associated with reduced oxidative stress and preserved mitochondrial function, but at supraphysiological levels it can induce reactive oxygen species accumulation, mitochondrial dysfunction, DNA damage, and apoptosis in both malignant and non-malignant skin cells. In one comparative study, high concentrations proved even more cytotoxic to normal fibroblasts than to carcinoma cells, suggesting a limited therapeutic window. Some melanoma cell lines, such as MNT-1, resisted significant growth inhibition altogether, and early clinical observations of high-dose melatonin in advanced melanoma, which reported partial responses and disease stabilization, came from small, non-randomized studies without matched controls, limiting their interpretability.

Pharmacokinetics present another hurdle for systemic use. Oral melatonin is rapidly absorbed, peaks in plasma within 30 to 60 minutes, and is cleared with a half-life of less than an hour, while extensive first-pass hepatic metabolism drives low and highly variable bioavailability. Plasma concentrations achieved in vivo typically fall in the pico- to nanomolar range, far below the supraphysiological levels used in many laboratory experiments. The authors argue that this makes topical delivery the more rational route for skin protection. Melatonin’s low molecular weight and moderate lipophilicity facilitate penetration through the stratum corneum, and topically applied hormone accumulates in epidermal and adnexal compartments, forming a local reservoir that sustains antioxidant and cytoprotective activity without systemic exposure. The molecule even absorbs UVB radiation directly, in the 280 to 320 nanometer range, adding a physical photoprotective component to its biochemical ones.

Human data on topical melatonin, though preliminary, are intriguing. Applied before UV exposure, it reduced UVB-induced erythema in a dose-dependent manner, and under natural sunlight only a 12.5 percent cream showed significant protection compared with placebo and untreated skin. Formulation studies have explored melatonin-based emulsions combined with physical UV filters and high sun protection factors, though the hormone’s sensitivity to light and oxidation demands carefully optimized vehicles to preserve bioactivity. On the therapeutic side, a Cochrane systematic review found that melatonin used alongside standard anticancer therapy probably reduced treatment-related fatigue and nausea, though certainty of evidence for survival and quality-of-life outcomes remains low. Experimental work in hepatocellular carcinoma models further suggests the hormone can suppress PD-L1 expression and enhance the efficacy of immune checkpoint inhibitors, a finding the authors flag as promising but not yet tested in skin cancer.

Older adults emerge as a particularly relevant population, since skin cancer incidence rises with age precisely as endogenous melatonin production declines. Yet aging skin may not respond uniformly to supplementation. An in vitro study documented an age-associated reduction of MT1 receptor expression in human dermal fibroblasts, and knocking down that receptor increased oxidative stress and UV-induced DNA damage, implying that receptor decline could blunt photoprotective responses. Still, an ex vivo study of aged human eyelid skin from donors aged 49 to 77 found that melatonin modified selected aging markers, including Matrix Metalloproteinase 1 expression, suggesting that aged skin retains at least selective responsiveness to the hormone.

The authors are careful to frame their conclusions as a hypothesis rather than a prescription. Most supporting data derive from preclinical models, human studies specifically designed for skin cancer prevention or treatment remain scarce, and no large randomized controlled trials have evaluated melatonin either as a preventive agent in high-risk populations or as an adjuvant in established melanoma and non-melanoma skin cancer. Timing matters as well: because DNA repair is rhythmically regulated, exogenous melatonin taken at the wrong circadian phase could theoretically disrupt endogenous clock dynamics and even increase UV sensitivity. If future research validates the hypothesis, however, the implications could extend beyond any pill or cream, pointing toward the preservation of biological rhythms and restorative sleep as genuine components of cancer prevention. For now, melatonin remains a molecule of remarkable biological plausibility awaiting its clinical trial moment in dermatologic oncology.

Subject of Research: The potential role of melatonin in the prevention and adjuvant treatment of skin cancer

Article Title: Could the use of melatonin be a promising complementary strategy in the prevention of skin cancer?

Article References: Altenfelder, L. A., Xerfan, E. M. S., Tufik, S., & Andersen, M. L. (2026). Could the use of melatonin be a promising complementary strategy in the prevention of skin cancer?. Archives of Dermatological Research, 318(1), Article 510. https://doi.org/10.1007/s00403-026-04933-9

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04933-9

Keywords: melatonin, skin cancer, melanoma, circadian rhythm, oxidative stress, UV radiation, DNA repair, p53, NRF2, topical melatonin, chemoprevention, sleep disorders

The review, conducted according to PRISMA 2020 guidelines and registered in PROSPERO, searched Web of Science, PubMed and EbscoHost for studies published between February 2020 and January 2026. From 404 initial records, 24 studies met the strict eligibility criteria: three addressed primary prevention, meaning measures that stop the disease from developing, and 21 addressed secondary prevention, meaning screening and early detection. The studies spanned North America, Europe and Asia and included one randomized controlled trial, nine diagnostic accuracy studies, thirteen conventional observational studies and one quality improvement study. Quality was assessed with established tools including the Cochrane Risk of Bias 2.0 instrument, the Newcastle-Ottawa Scale and QUADAS-2, and the certainty of the evidence was graded using the GRADE framework.

The epidemiological backdrop gives the work its urgency. According to the Global Cancer Observatory, more than 330,000 new cases of cutaneous melanoma were reported in 2020, with nearly 59,000 deaths, translating into a mortality rate of 17.7 percent. Incidence is rising by 3 to 7 percent each year, doubling every 10 to 20 years, and the International Agency for Research on Cancer predicts an increase of more than 50 percent in new annual cases between 2020 and 2040. Fair-skinned populations in high-UV regions such as Australia, Europe and North America carry the greatest burden, and ultraviolet radiation, particularly intense intermittent exposure, remains the dominant external risk factor, driving the DNA damage and oncogenic mutations, including BRAF and NRAS alterations, that underpin melanomagenesis.

On the primary prevention front, the pickings were slim but intriguing. Two observational analyses of extended follow-up from a large Australian randomized trial, involving 19,114 participants, examined whether daily 100-milligram aspirin could prevent melanoma. In hypertensive individuals, aspirin use was associated with a 27 percent reduction in melanoma incidence, with a hazard ratio of 0.73, and the effect was strongest among those with uncontrolled hypertension. Yet in older participants overall, the same dataset showed no statistically significant benefit, with a hazard ratio of 1.04. The reviewers graded this evidence as low certainty, noting that both analyses come from the same research group and that aspirin carries well-known bleeding risks, so no clinical recommendation can be made until large, independent randomized trials clarify the risk-benefit balance.

The third primary prevention study, from Greece, took a different angle, examining total body nevus counts in 813 people. It confirmed that mole counts decline with age, with people over 51 having a 73 percent lower likelihood of carrying 30 to 60 nevi, and that taller individuals showed a steeper decline, particularly women. The finding hints at genetic mechanisms governing nevus dynamics, echoing genome-wide association work that has identified dozens of loci linking nevus count to melanoma susceptibility. Notably, the search found no new studies on sunscreen formulation or photoprotection during the review window, suggesting that after decades of successful sun-safety campaigns, research energy has migrated decisively toward early detection technology.

That migration is most visible in the eight studies evaluating artificial intelligence for melanoma detection. The review organized these tools into three generations. Classical machine learning, including support vector machines and random forests, requires experts to manually define image features. Deep learning, built on convolutional neural networks such as DenseNet and EfficientNet, learns features automatically from large labeled image sets. The newest approach, self-supervised learning, needs no labeled data at all: in a Swiss study, a self-supervised system combining object detection with vision transformers achieved 95 percent sensitivity in flagging suspicious lesions, and raised the sensitivity of medical students from roughly 63 to 68 percent up to 81 to 82 percent, matching expert dermatologists at 100 percent agreement.

Across the AI studies, specificity ranged from 70.4 to 100 percent, often matching that of specialists, but sensitivity varied widely, from 58.3 percent in two-dimensional total body photography systems to 89 percent in dermoscopic models. Three-dimensional convolutional neural networks outperformed their two-dimensional counterparts, and combining dermatologist judgment with 3D analysis improved accuracy further. Yet the review flagged consistent caveats: consumer-facing smartphone apps underperformed tools embedded in clinical settings with professional oversight; performance dropped in difficult areas such as tattoos, skin folds and hairy regions; and nearly all studies enrolled predominantly fair-skinned, Fitzpatrick type I and II patients, leaving darker phototypes dangerously underrepresented. The reviewers also raised an environmental concern, noting that the energy and water consumption of training self-supervised systems at community screening scale could be unsustainable.

Beyond AI, conventional secondary prevention showed real-world value. A five-year screening initiative in a large US health system, covering nearly 600,000 patients, diagnosed significantly more thin melanomas, those measuring 1 millimeter or less, among screened patients, while thick lesions trended downward. Free beachside screening events in Rhode Island achieved a number needed to screen of just 18.3. Longitudinal surveillance of melanoma-prone families reduced mean tumor thickness at diagnosis from 1.1 to 0.6 millimeters, with 83 percent of prospectively detected tumors classified as early-stage T1 versus 40 percent before the program. Remote training in skin self-examination proved as effective as in-person instruction in a randomized trial of 341 melanoma survivors and their partners, and community pharmacy-based teledermatology in Spain achieved more than 85 percent diagnostic accuracy on submitted photographs, opening a low-threshold referral route for the public.

Two emerging technologies rounded out the review. Hyperspectral imaging paired with deep learning distinguished melanoma from benign nevi with 98 percent accuracy using two-dimensional spectral-spatial data, exploiting spectral differences concentrated in the 500 to 675 nanometer band. Even more futuristic is a wearable microneedle patch developed in China, studded with hundreds of tiny tips and gold-silver nanospheres, that measures tyrosinase, the rate-limiting enzyme of melanin synthesis, directly within suspicious skin lesions using surface-enhanced Raman spectroscopy, with an ultralow detection limit of 0.01 units per milliliter. Because tyrosinase activity is elevated in malignant melanocytes, the reviewers suggest this painless biosensor could one day offer an objective, early biomarker, provided it remains affordable and accurate over time.

The overall message is one of cautious optimism. Advanced imaging combining three-dimensional total body photography, digital dermoscopy and reflectance confocal microscopy currently carries the highest certainty of evidence for early diagnosis, but demands specialist infrastructure. AI tools are sensitive but not yet specific enough, and must be validated across all skin tones before widespread deployment. Aspirin remains a hypothesis, not a prescription. What the review makes clear is that the future of melanoma prevention will likely be hybrid: sun protection and expert-led examination as the foundation, augmented by algorithms, biosensors and genomics, always under the supervision of dermatologists, to catch the world’s deadliest skin cancer while it is still thin, treatable and curable.

Subject of Research: Primary and secondary prevention strategies for cutaneous melanoma, including AI-based screening, chemoprevention and emerging biomarkers

Article Title: New Primary and Secondary Prevention Measures for Cutaneous Melanoma: A Systematic Review

Article References: Palau–del–Valle, M., Bendala–Tufanisco, E., & López–Ruiz, M. A. (2026). New Primary and Secondary Prevention Measures for Cutaneous Melanoma: A Systematic Review. Cancer Reports, 9(10), Article e70698. https://doi.org/10.1002/cnr2.70698

Image Credits: AI Generated

DOI: 10.1002/cnr2.70698

Keywords: cutaneous melanoma, systematic review, artificial intelligence, screening, aspirin chemoprevention, tyrosinase biosensor, total body photography, dermoscopy, UV radiation, early detection, convolutional neural networks, public health

The biology behind the risk is unforgiving. Ultraviolet radiation inflicts structural damage on DNA in skin cells, and while the body’s antioxidant repair mechanisms normally cope, saturation of those systems tips the balance toward carcinogenesis. Chronic exposure also degrades skin structure, suppresses immune defenses in the skin, and damages the eyes, contributing to cataracts, keratitis, and pterygium. At altitude the danger is amplified because UV radiation travels a shorter distance through the atmosphere before striking the skin. Peru’s national weather service classifies UV levels across much of the Andean region as extremely high, and the country’s Ministry of Health recorded 3,525 cases of skin cancer between 2021 and 2023. Malignant melanoma, the most aggressive form of the disease, is the third most common cancer among Peruvians aged fifteen to thirty-nine, yet an estimated nine in ten cases are attributable to UV exposure, which makes it one of the most preventable cancers anywhere.

What makes the Andean situation distinctive is that sun exposure is not a seasonal or recreational hazard but a constant of daily life. Outdoor agricultural work, walking to school, and everyday recreation all unfold under a relentless sun, and in many rural communities this exposure is so normalized that it is not perceived as a health risk at all. Adolescents are particularly exposed through school activities and farm labor, while often lacking access to health information and services. Previous photoprotection studies in Peru and across Latin America have focused mostly on urban or peri-urban primary school children, leaving rural high-altitude adolescents, the group facing the highest cumulative UV loads, largely unstudied.

The research team, led by Yadhira Grecia Otazu Masco, Lizbeth Huarilloclla Ramos, and Lucy Puno-Quispe, worked with thirty-seven students aged thirteen to seventeen at a public rural school. With only two intact third-year sections available, one classroom of eighteen students served as the control group and the other, nineteen students, received the intervention. The design was quasi-experimental: both groups completed identical assessments before and after the two-month program, and the researchers used analysis of covariance to statistically adjust for any baseline differences between the groups. Notably, no students dropped out or were excluded, so the final sample matched the full enrolled cohort.

The INTI program itself was built for the classroom rather than the clinic. It consisted of twelve in-person sessions of forty-five minutes each, delivered twice weekly over two months, a duration chosen because habit-formation research suggests healthy behaviors typically need two to five months to consolidate. The sessions progressed from the biology of sun exposure and skin phototypes through sunburn, protective practices, sunscreen use, the emotional dimensions of skin health, the value of early prevention, nutrition and hydration, and even the legislation surrounding sun protection. Each session followed the ARDE methodology, a four-stage pedagogical structure of animation, reflection, demonstration, and evaluation, which pushed students beyond passive listening into repeated hands-on practice.

Measurement relied on the CHACES questionnaire, a validated Spanish-language instrument covering sun-exposure habits, attitudes, and knowledge of sunburn prevention. The team first checked content validity with a panel of seven expert judges, five physicians and two community health nurses, yielding an Aiken’s V coefficient of 0.91, then pilot-tested the instrument with fifteen comparable secondary students, producing a preliminary Cronbach’s alpha of 0.73. Baseline testing confirmed the two classrooms started on equal footing, with no statistically significant pretest differences in knowledge, habits, or attitudes.

The posttest results showed a consistent advantage for the INTI group across all three dimensions. After adjusting for baseline scores, the intervention group scored significantly higher on knowledge (F = 4.93, p = 0.033), habits (F = 20.3, p < 0.001), and attitudes (F = 6.03, p = 0.019). The largest effect, by a wide margin, appeared in habits, which accounted for roughly thirty-seven percent of the variance in posttest scores, a substantial effect size for an educational intervention. The pattern behind this number is revealing: the control group’s habit scores actually declined from pretest to posttest while the experimental group’s rose, and that divergence, rather than a mere difference in improvement rates, drove the adjusted difference. Attitudes barely moved in the control group, suggesting this dimension may resist change without direct intervention, while knowledge improved in both classrooms, hinting that some informational gains may occur regardless of a formal program.

The researchers attribute the outsized habit effect to the structure of INTI itself. Because several sessions were organized around repeated practice and demonstration, drawing on the reflection and demonstration stages of the ARDE methodology, the program may have engaged the behavioral machinery of habit formation more directly than purely cognitive lessons could. This interpretation aligns with a broader literature: a multicomponent sun-safety intervention with 106 middle schoolers improved knowledge and attitudes, and systematic reviews of school-based photoprotection programs across childhood and adolescence consistently report gains in both knowledge and protective behavior. The Andean results also contrast sharply with findings among adult agricultural workers, many of whom remained unaware of the risks of prolonged exposure and reluctant to use sunscreen, suggesting that reaching people before adulthood, when habits are still plastic, may be the decisive window.

The study’s context matters as much as its statistics. Earlier work has shown that parental knowledge of photoprotection predicts children’s protective practices, and that parent-targeted education can improve children’s sun behaviors, pointing toward a natural extension of INTI that brings caregivers into the program. Gender differences in photoprotection habits documented elsewhere also argue for tailored content. And while digital tools such as a facial-aging web application have produced sustained behavior change over three-month follow-ups, follow-up duration alone does not reliably predict lasting protection; poverty and limited access to health services, both prevalent in rural Puno, shape whether protective habits take root at all.

The authors are appropriately candid about the limits of their evidence. Randomization occurred at the classroom level with only one classroom per condition, so group membership is confounded with classroom membership and the independence of individual observations may not hold. Convenience sampling, the small sample of thirty-seven, and the absence of data on family influence, economic constraints, or cultural norms all restrict generalizability, and the self-reported outcomes were captured at a single posttest point, leaving open whether the changes persist. Still, as preliminary evidence, the study makes a compelling case for embedding photoprotection education in rural school curricula, training teachers and health staff, and ensuring access to UV protection products in regions where the sun is an inescapable fact of geography. For the teenagers of the high Andes, whose skin absorbs a lifetime of ultraviolet damage before they finish secondary school, twelve structured classroom sessions may prove one of the cheapest and most effective cancer-prevention tools available.

Subject of Research: Effectiveness of a school-based photoprotection education program among adolescents in a high-altitude rural Andean region

Article Title: Effectiveness of INTI educational program on photoprotection among adolescents in high-altitude rural Andean school: A quasi-experimental study

Article References: Otazu Masco, Y. G., Huarilloclla Ramos, L., & Puño-Quispe, L. (2026). Effectiveness of INTI educational program on photoprotection among adolescents in high-altitude rural Andean school: A quasi-experimental study. Public Health in Practice, 12, Article 100853. https://doi.org/10.1016/j.puhip.2026.100853

Image Credits: AI Generated

DOI: 10.1016/j.puhip.2026.100853

Keywords: photoprotection, UV radiation, skin cancer, adolescents, Andes, Peru, sun safety education, quasi-experimental study, public health, melanoma prevention, school health program, high altitude

The therapeutic material, known as a secretome, is the complete collection of bioactive molecules that stem cells release into their surroundings, including growth factors, cytokines, nucleic acids such as microRNAs, lipid metabolites, and extracellular vesicles like exosomes. Mounting evidence suggests that the clinical benefits of mesenchymal stem cells come not from the cells themselves engrafting and replacing worn-out tissue, but from these paracrine signals. That insight has fueled interest in secretome-based therapies as safer, more controllable alternatives to live-cell transplantation, eliminating risks of rejection, uncontrolled proliferation, or tumorigenicity. Human umbilical cord-derived mesenchymal stem cells are especially attractive sources because they are readily available, ethically uncontroversial, non-invasive to procure, and expand vigorously in culture. Prior work by the same team showed that this secretome could stimulate hair growth through the PI3K/AKT/mTOR pathway, but its role in photoaging had remained poorly defined.

To test the secretome’s anti-aging potential, researchers at Southern Medical University in Guangzhou, China, built a chronic photoaging model in mice. Over 40 days, depilated dorsal skin was irradiated with a carefully calibrated mixture of UVA and UVB whose intensity ratio of roughly 6.7 to 1 mirrors the spectral balance of natural sunlight reaching Earth’s surface. Doses escalated gradually from 10 to 30 minutes per day, avoiding the acute burns that plague many UV experiments and instead mimicking the cumulative, sub-erythemal sun exposure that ages human skin in real life. The mice developed the expected phenotype: leathery thickening, erythema, scaling, and a measurable collapse in skin elasticity, hydration, and barrier function as water loss through the epidermis climbed. Topical application of the secretome, delivered as 200 microliters daily for 30 days beginning after an adaptation period, visibly and statistically reversed nearly all of it.

Histology told the same story at the tissue level. Hematoxylin and eosin staining revealed that UV-driven epidermal hyperplasia and dermal thickening were substantially attenuated by the treatment. Masson’s trichrome staining showed that chronic irradiation had fragmented and depleted the dermal collagen network, the structural scaffold that keeps skin firm, while secretome-treated skin retained intact collagen fibers and significantly greater total collagen content. Immunohistochemistry and Western blotting traced the molecular basis: UV exposure suppressed the structural collagens COL1 and COL3 while ramping up the matrix-degrading enzymes MMP1, MMP3, and MMP9, and the secretome normalized all of these shifts. Senescence markers responded in parallel. The nuclear envelope protein Lamin B1, which declines as cells age, was restored to near-normal levels, while the cell-cycle inhibitors p16 and p21, elevated by UV stress, were pushed back down.

Notably, the treatment showed a reassuring safety profile. In mice that received the secretome without any UV exposure, modest improvements in hydration and water-loss parameters were observed, indicating support for barrier function under normal conditions, but there was no epidermal or dermal thickening and no alteration of collagen turnover. In other words, the therapy behaves differently depending on context: gentle maintenance when skin is healthy, active repair when skin is damaged. That stress-responsive selectivity matters for any candidate cosmetic or clinical intervention, because it suggests the secretome is not forcing skin into an abnormal proliferative state but rather helping stressed tissue recover its equilibrium.

The mechanistic heart of the study lies in mitochondria, the energy-producing organelles that are both a primary source of reactive oxygen species and particularly vulnerable to UV damage. Chronic irradiation mutates mitochondrial DNA, breaks respiratory chain function, and floods cells with oxidative stress, creating a vicious cycle that drives senescence. Cells normally dispose of dysfunctional mitochondria through mitophagy, a selective autophagy process that tags damaged organelles and delivers them to lysosomes for destruction. The classical PINK1/Parkin pathway orchestrates much of this quality control. Using transmission electron microscopy, the team documented severe mitochondrial injury in UV-exposed skin, including matrix swelling and fragmented cristae, alongside accumulation of mitochondrial proteins TOM20, TIM23, and HSP60 and the autophagy adaptor p62, all signs of clogged disposal machinery. The secretome reversed every one of these defects, restored PINK1 and Parkin levels, and boosted the fusion of mitochondria with lysosomes, confirmed by confocal imaging and colocalization statistics.

Why does clearing broken mitochondria matter so much for aging? The answer lies in a second pathway: cGAS-STING, the innate immune circuit that senses misplaced DNA. When damaged mitochondria leak their DNA into the cytoplasm, the sensor protein cGAS mistakes this self-DNA for a viral invader and synthesizes the messenger cGAMP, which activates STING and triggers a phosphorylation cascade through TBK1, IRF3, and IKK. The result is a flood of type I interferons and inflammatory cytokines, including IL-6, IL-8, and IFN-beta, a chronic low-grade inflammation researchers call inflammaging. The study showed this pathway roaring to life in UV-irradiated mouse skin and UVB-exposed human keratinocytes, with cytosolic double-stranded DNA accumulating visibly under the microscope. Secretome treatment shut the whole cascade down, from cGAS expression through cytokine secretion, both in tissue and in serum.

The causal architecture was tested with an elegant pharmacological epistasis design. The mitophagy inhibitor Mdivi-1, which blocks the fission protein Drp1, abolished the secretome’s protective effect and reactivated cGAS-STING signaling, elevating inflammatory cytokines and restoring senescence markers. Conversely, the mitophagy agonist CCCP mimicked the secretome’s benefits on its own, while the STING inhibitor H151 enhanced protection further. Most tellingly, when Mdivi-1 and H151 were combined, H151 bypassed the mitophagy blockade entirely and restored full protection, demonstrating that STING sits downstream of mitophagy in a strict hierarchy: the secretome protects skin primarily by reactivating mitochondrial housekeeping, which prevents DNA leakage and thereby disarms the inflammatory driver of senescence.

The implications reach well beyond dermatology. The mitophagy-cGAS-STING axis has been implicated in neurodegeneration and cardiac hypertrophy, and this study provides direct in vivo evidence that the same cascade operates in skin aging and can be therapeutically targeted by a cell-free biologic. A standardized secretome, harvested from a single validated donor batch, sterile-filtered, and frozen in aliquots, could sidestep many regulatory and safety hurdles of live-cell therapy while remaining simple to apply topically. The authors caution that murine skin and immortalized keratinocyte lines cannot fully recapitulate human biology, and clinical validation will be essential before any anti-aging product reaches the clinic. Still, the demonstration that boosting a cellular waste-disposal system can quiet an inflammatory aging program offers a compelling mechanistic template, not just for smoother skin, but potentially for a broad class of mitochondrial-driven age-related disorders.

Subject of Research: Cell-free mesenchymal stem cell secretome therapy for skin photoaging via the mitophagy-cGAS-STING axis

Article Title: The Secretome Derived From Human Umbilical Cord Mesenchymal Stem Cells Improves Skin Photoaging by Enhancing Mitophagy to Inhibit the cGAS‐STING Pathway

Article References: Tang, T., Lin, M., Yang, J., Yang, X., Xu, X., Wang, X., Zhang, Y., Chen, Q., Zhao, S., Guo, C., Zhang, H., Zhang, M., Zhang, L., & Wang, X. (2026). The Secretome Derived From Human Umbilical Cord Mesenchymal Stem Cells Improves Skin Photoaging by Enhancing Mitophagy to Inhibit the cGAS ‐ STING Pathway. Aging Cell, 25(9), Article e70701. https://doi.org/10.1111/acel.70701

Image Credits: AI Generated

DOI: 10.1111/acel.70701

Keywords: skin photoaging, mesenchymal stem cells, secretome, mitophagy, cGAS-STING, inflammaging, UV radiation, keratinocytes, cell-free therapy, collagen degradation, senescence, regenerative dermatology