The stakes of the question are considerable. Multi-agent neoadjuvant therapy, meaning chemotherapy given before surgery, combined with the immune checkpoint inhibitor pembrolizumab, is the established standard for Stage II and III triple-negative breast cancer. That standard rests largely on the landmark KEYNOTE-522 trial, which showed that adding immunotherapy to neoadjuvant chemotherapy improved pathologic complete response rates, event-free survival, and overall survival. But the pivotal trials that cemented this approach either excluded patients with Stage I disease or failed to analyze them separately, leaving clinicians without direct evidence for the smallest tumors. Current National Comprehensive Cancer Network guidelines still recommend upfront surgery followed by adjuvant chemotherapy for node-negative tumors measuring one to two centimeters, reserving neoadjuvant strategies for higher-risk cases.

In practice, however, the lines are blurring. Neoadjuvant therapy offers real advantages: it tests a tumor’s chemosensitivity in the body, can shrink cancers enough to enable breast-conserving surgery, and provides a powerful prognostic signal. Patients who achieve a pathologic complete response, defined as no residual invasive disease at surgery, have excellent outcomes, while those with residual disease can be escalated to treatments such as adjuvant capecitabine, validated in the CREATE-X trial, or olaparib for patients with germline BRCA mutations, validated in the OlympiA trial. These residual-disease-directed strategies have given clinicians a practical reason to give therapy up front even when a tumor is small, since the response itself guides what happens next.

To map the contemporary landscape, the researchers assembled a cohort of 252 patients with T1-2N0M0 triple-negative breast cancer diagnosed between July 2021 and December 2024, then focused on a predefined small TNBC group of 215 patients: 154 with Stage I disease and 61 with node-negative Stage II tumors smaller than three centimeters. The cohort was demographically typical of triple-negative disease, with 82.5 percent grade 3 histology and 89.3 percent ductal histology. Overall, 70.6 percent of patients received neoadjuvant therapy, 98.8 percent underwent surgery, and 42.1 percent received adjuvant radiation. With a median follow-up of 2.6 years, recurrence occurred in 18 patients and death in 11, reflecting the generally favorable prognosis of small, node-negative tumors.

The most striking finding was the asymmetry between biology and treatment. Demographically, the Stage I and small Stage II groups were nearly indistinguishable, with similar ages, menopausal status, comorbidities, and BRCA mutation prevalence. Histopathologically they overlapped as well, although grade 3 histology was more common in the Stage II, under-three-centimeter group. Yet treatment diverged sharply. Neoadjuvant therapy was given to 85.2 percent of small Stage II patients versus 61.0 percent of Stage I patients. The KEYNOTE-522 regimen, combining chemotherapy with pembrolizumab, dominated both groups but was used far more often in Stage II disease, at 75.0 percent versus 45.7 percent. Adjuvant pembrolizumab followed the same pattern, given to 56.8 percent of small Stage II patients compared with 24.7 percent of Stage I patients.

Despite these markedly different treatment intensities, outcomes converged. Recurrence rates were 6.5 percent in the small Stage II group versus 3.3 percent in Stage I, and mortality rates were 1.9 percent versus 6.6 percent, neither difference statistically significant. Among the 146 patients treated with neoadjuvant therapy, the pathologic complete response rate was 51.3 percent overall, and it was essentially identical across the stage boundary: 51.1 percent for Stage I versus 51.9 percent for small Stage II tumors. No individual regimen separated itself from the pack. KEYNOTE-522 achieved a pCR rate of 52.4 percent in the combined small TNBC cohort, statistically indistinguishable from anthracycline-taxane regimens at 50.0 percent, carboplatin-taxane plus pembrolizumab at 45.8 percent, and other neoadjuvant approaches at 55.0 percent.

Survival analyses told a similar story of convergence. Event-free survival did not differ significantly between patients who received neoadjuvant therapy and those who did not within the small TNBC cohort, nor between Stage I and small Stage II patients treated with neoadjuvant therapy. Even within the KEYNOTE-522-treated subgroup, event-free survival did not significantly differ by stage. The authors caution that these survival findings are exploratory, limited by short follow-up, few events, and the selection biases inherent in any retrospective design. Treatment assignment was not randomized, and confounding by indication, in which sicker-appearing patients receive more intensive therapy, cannot be excluded. Subgroups were also small, precluding robust multivariable modeling.

Still, the pattern is clinically meaningful. The authors note that immune checkpoint inhibitors can produce durable endocrinopathies such as adrenal insufficiency or insulin-dependent diabetes, toxicities that weigh heavily in patients whose tumors already carry a favorable prognosis. Intensifying therapy for a two-centimeter node-negative tumor while withholding the same regimen from a 2.1-centimeter tumor, purely because it crosses an arbitrary size threshold, may not reflect underlying biology. The data suggest that node-negative tumors just below and above the two-centimeter T1c-T2a boundary may behave more alike than staging conventions assume, and that a size-based framework for small triple-negative breast cancer could better contextualize treatment decisions than the current stage-based one.

The study team is already moving toward prospective answers. Their center is conducting DETENTE-1, a phase 2 randomized pilot study in Stage I triple-negative breast cancer comparing three neoadjuvant strategies: carboplatin plus paclitaxel, carboplatin plus paclitaxel plus pembrolizumab, and pembrolizumab monotherapy. Such de-escalation trials could identify which small tumors truly need intensified chemoimmunotherapy and which can be spared its costs. The authors envision integrated risk-stratification models incorporating tumor size, genomic data, immune biomarkers, toxicity risk, and cost considerations to individualize neoadjuvant selection. For now, the message for patients and clinicians is nuanced: small node-negative triple-negative breast cancers respond to modern therapy at high rates and with low recurrence, but the evidence base for choosing among regimens remains thin, and the conventional stage boundary may be a poorer guide to biology than anyone assumed.

Subject of Research: Neoadjuvant therapy patterns and outcomes in small node-negative triple-negative breast cancer

Article Title: Contemporary therapy for small node-negative triple-negative breast cancer: a retrospective cohort study

Article References: Lee, B., Santos, B., McArthur, H., LeVee, A., Kordic, A., Zhang, S., & J. Gruber, J. (2026). Contemporary therapy for small node-negative triple-negative breast cancer: a retrospective cohort study. Breast Cancer Research and Treatment, 219(3), Article 15. https://doi.org/10.1007/s10549-026-08074-5

Image Credits: AI Generated

DOI: 10.1007/s10549-026-08074-5

Keywords: triple-negative breast cancer, neoadjuvant therapy, pembrolizumab, KEYNOTE-522, pathologic complete response, Stage I breast cancer, immunotherapy, cancer staging, treatment de-escalation, retrospective cohort study, event-free survival, breast-conserving surgery

Triple-negative breast cancer is defined by the absence of the three molecular handles that anchor most modern breast cancer therapy: the estrogen receptor, the progesterone receptor, and HER2. Without those targets, endocrine agents and HER2-directed drugs are ineffective, leaving cytotoxic chemotherapy as the systemic backbone of treatment. Although triple-negative tumors account for only about 10 to 15 percent of breast cancers, they carry a disproportionate share of the disease’s mortality because they tend to grow quickly, are more likely to metastasize, and historically have fewer therapeutic options. For patients whose tumors are caught early, the central treatment question is not whether chemotherapy helps but when it should be given.

That question is most acute for T1c tumors, which measure between one and two centimeters and have not spread to regional lymph nodes or distant sites. The T1cN0M0 designation describes a small, node-negative cancer, yet even at this stage triple-negative biology demands systemic therapy to reduce recurrence risk. The debate concerns sequencing. Neoadjuvant chemotherapy, delivered before surgery, offers the chance to shrink the tumor, potentially enabling less extensive operations, and provides real-time information about how the cancer responds to treatment. Adjuvant chemotherapy, given after surgery, achieves the same cytotoxic goal but leaves the surgeon operating on a tumor that has never been exposed to drugs. National guidelines leave room for either approach in this small-tumor setting, and practice varies considerably across institutions.

The reason sequencing remains contested is that neither strategy has demonstrated superior overall survival. Multiple prior analyses, including studies of the same National Cancer Database, have found that patients with clinically node-negative T1 triple-negative tumors fare equally well whether chemotherapy comes first or last. If survival outcomes are equivalent, the choice between the two approaches hinges on secondary benefits: the possibility of breast-conserving surgery, the prognostic information embedded in treatment response, and patient preference. The Johns Hopkins team, led by breast surgical oncology researcher Andrew Venardi, set out to sharpen that calculus by asking a more granular question: within this seemingly uniform early-stage population, which patients are actually likely to benefit from going first with chemotherapy?

The answer, they hypothesized, might lie in Ki-67, a nuclear protein expressed by cells that are actively dividing. Pathologists measure Ki-67 by immunohistochemistry, staining tumor samples and counting the percentage of positive cells, which yields a proliferation index reflecting how fast the cancer is growing. The logic connecting Ki-67 to neoadjuvant strategy is mechanistically straightforward: chemotherapy agents such as anthracyclines and taxanes preferentially kill rapidly proliferating cells, so tumors with a high fraction of dividing cells should, in principle, be more sensitive to upfront drug treatment. Previous studies have associated high Ki-67 expression with better responses to neoadjuvant chemotherapy in triple-negative disease, but the specific threshold that separates responders from non-responders in the earliest tumor category had not been clearly defined using large-scale national data.

To conduct the analysis, the researchers queried the National Cancer Database for female patients aged 18 and older diagnosed with T1N0M0 triple-negative breast cancer between 2018 and 2022 who underwent both chemotherapy and surgery. The National Cancer Database, jointly maintained by the American College of Surgeons and the American Cancer Society, captures roughly 70 percent of newly diagnosed cancer cases in the United States, providing the statistical power that single-institution series cannot match. Patients were divided into a neoadjuvant chemotherapy cohort and an adjuvant chemotherapy cohort. Because the two groups differ systematically in tumor size, grade, and other characteristics—surgeons and oncologists tend to select patients for upfront chemotherapy based on perceived risk—the team applied inverse probability of treatment weighting, a statistical technique that re-weights the cohorts to mimic the balance of a randomized trial.

The survival analysis produced a finding consistent with the existing literature: overall survival did not differ significantly between the neoadjuvant and adjuvant groups. Multivariate Cox regression, which adjusts for competing variables simultaneously, instead identified three factors associated with worse survival. Lymphovascular invasion, the presence of tumor cells within small blood or lymphatic vessels, signaled a higher risk of microscopic spread. The invasive lobular subtype, which arises in the milk-producing lobules rather than the ducts, and mixed lobular-ductal tumors were also linked to poorer outcomes. Lobular triple-negative cancers are rare and biologically distinct, and recent registry-based studies have shown they can carry worse survival despite appearing indolent, so their emergence as an adverse marker in this dataset aligns with a growing body of evidence.

The most consequential result came from the response analysis. Among patients who received neoadjuvant chemotherapy, those who achieved a pathologic complete response—meaning no residual invasive cancer was found in the breast or lymph nodes at the time of surgery—had markedly better survival than those who did not. Non-responders faced a hazard ratio of 3.59 for worse overall survival compared with patients who achieved a complete response. This echoes the findings of a large meta-analysis showing that pathologic complete response in triple-negative breast cancer is strongly associated with improved long-term event-free and overall survival. In other words, while the timing of chemotherapy may not change survival on average, achieving eradication of the tumor before surgery identifies a subgroup whose prognosis is transformed.

That is where the Ki-67 threshold enters. Using a receiver operating characteristic curve, the researchers plotted the relationship between Ki-67 expression and pathologic complete response and applied the maximum Youden index, a standard method for finding the cutoff point that best balances sensitivity and specificity. The threshold that emerged was 45.8 percent. Patients whose tumors expressed Ki-67 at or above that level achieved a pathologic complete response rate of 45.3 percent, while those below it responded at a rate of only 21.8 percent. Expressed differently, a high proliferation index more than doubled the odds that upfront chemotherapy would completely eliminate the tumor. Logistic regression confirmed Ki-67 expression as an independent predictor of complete response, suggesting the association held after accounting for other tumor characteristics.

The clinical implications are tangible for a patient population that often faces an anxious choice. A woman with a 1.5-centimeter, node-negative triple-negative tumor whose biopsy shows a Ki-67 index of 50 percent now has registry-scale evidence that chemotherapy before surgery is likely to produce a complete response, with the dual benefits of maximal prognostic information and a survival outcome that appears markedly better than that of non-responders. Conversely, a patient with a low proliferation index may reasonably opt for surgery first, since her probability of achieving a complete response is lower and adjuvant chemotherapy delivers equivalent survival. The authors emphasize that the study is retrospective and that Ki-67 measurement itself has well-known variability between laboratories and staining protocols, so the 45.8 percent cutoff should be validated prospectively before it reshapes guidelines. Still, as the field moves from one-size-fits-all recommendations toward personalized sequencing in stage I triple-negative breast cancer, a routine pathology marker already on every diagnostic report may prove to be the deciding variable.

Subject of Research: Ki-67 expression as a predictor of pathologic complete response to neoadjuvant chemotherapy in early-stage triple-negative breast cancer

Article Title: Ki-67 expression and rates of pathologic complete response in T1cN0M0 triple-negative breast cancer: a national cancer database analysis

Article References: Venardi, A., Shojaeian, F., Diaz, S., Schuster, C. R., Rath, P., Shaid, I., Singh, A., Santa-Maria, C., & Sogunro, O. (2026). Ki-67 expression and rates of pathologic complete response in T1cN0M0 triple-negative breast cancer: a national cancer database analysis. Breast Cancer Research and Treatment, 219(3), Article 21. https://doi.org/10.1007/s10549-026-08086-1

Image Credits: AI Generated

DOI: 10.1007/s10549-026-08086-1

Keywords: triple-negative breast cancer, Ki-67, neoadjuvant chemotherapy, pathologic complete response, National Cancer Database, T1cN0M0, proliferation index, biomarker, breast surgical oncology, lymphovascular invasion, invasive lobular carcinoma, personalized treatment

A retrospective study published in Breast Cancer Research and Treatment followed 284 women with node-positive breast cancer who received neoadjuvant chemotherapy, the chemotherapy administered before surgery with the goal of shrinking tumors and, in some patients, eradicating nodal disease entirely. The analysis, conducted by a team at the University of Pittsburgh led by Callie Hlavin and Emilia J. Diego, compared patients who underwent full axillary lymph node dissection with those who received targeted axillary dissection, a deliberately limited procedure that removes only the previously involved, marked lymph node along with nearby sentinel nodes. With a median follow-up of 36.3 months, the researchers found no meaningful difference in recurrence, mortality, disease-free survival, or overall survival between the two operations in either of the clinical groups they examined.

The study exploited a technical innovation that has reshaped how surgeons think about the axilla after neoadjuvant chemotherapy. Before treatment begins, the biopsy-proven cancerous lymph node is marked — in this study, with a radioactive iodine seed — so that the same node can be identified and removed after chemotherapy, even if the tumor inside it has completely disappeared. This approach, known as targeted axillary dissection or TAD, allows surgeons to re-examine the very node that harbored cancer at diagnosis, dramatically reducing the false-negative rate compared with sentinel lymph node biopsy alone. After surgery, patients are divided into two groups based on what pathologists find in that recovered node: those with a complete pathologic response, meaning the diseased node shows no residual cancer, and those with persistent disease.

Of the 284 patients, 128 achieved a complete pathologic response in the marked node, designated dSLN-negative. Only 13 of these women went on to receive a full axillary dissection, while 115 — roughly 90 percent — were managed with targeted axillary dissection alone. The remaining 156 patients still had cancer in the marked node after chemotherapy, designated dSLN-positive; 107 of them underwent full axillary lymph node dissection and 49 received targeted dissection. This distribution reflects an evolving practice pattern in which surgeons increasingly feel comfortable omitting the full dissection when the marked node shows eradication of disease, and the Pittsburgh data now provide some of the most direct evidence yet that this comfort is justified.

The survival figures are striking for their equivalence. Among patients with a complete response in the marked node, mortality was 15.4 percent after full axillary dissection versus 8.9 percent after targeted dissection, a difference that did not approach statistical significance. Disease-free survival averaged 19.6 months in the dissection group and 30.7 months in the targeted group, and overall survival was 49.3 versus 45.8 months — again, without significant differences. Among patients with persistent disease in the marked node, mortality was 9.3 percent with targeted surgery versus 10.2 percent with full dissection, disease-free survival was 30 versus 37 months, and overall survival was nearly identical at 36.4 versus 36.2 months. Across every measure the investigators tracked — frequency of recurrence, location of recurrence, death, disease-free survival, and overall survival — the extent of axillary surgery made no difference.

One nuance deserves attention. In the group with persistent nodal disease, the researchers observed a higher frequency of recurrence among patients who underwent full axillary lymph node dissection compared with those who had targeted dissection. That finding runs counter to the traditional assumption that removing more nodes always confers better local control, though the investigators caution that it did not translate into any difference in disease-free or overall survival, and the retrospective design and modest subgroup sizes limit how much weight the observation can bear. What it does underscore is the central paradox that has driven the de-escalation movement: decades of trials have shown that additional axillary surgery does not reliably improve survival, even when it changes local recurrence patterns.

The scientific rationale for trimming axillary surgery rests on biology as much as surgical outcomes. Neoadjuvant chemotherapy can completely eradicate nodal metastases in a substantial fraction of node-positive patients, and that pathologic response is among the most powerful prognostic markers in breast cancer. Systemic therapy circulating throughout the body treats microscopic disease wherever it resides, while regional nodal surgery mainly serves staging and local control. Landmark trials such as ACOSOG Z0011 demonstrated that omitting full dissection in selected sentinel-node-positive patients did not compromise survival, and studies including ACOSOG Z1071, SENTINA, and SN FNAC established that sentinel node biopsy after neoadjuvant chemotherapy is technically feasible — provided the previously positive node itself is identified and removed, which is precisely what radioactive seed marking and targeted dissection accomplish.

The stakes of this debate are far from academic. Axillary lymph node dissection removes a large volume of lymphatic tissue and is a leading cause of lymphedema, the chronic, sometimes disabling swelling of the arm that can follow breast cancer treatment. It is also associated with shoulder stiffness and reduced range of motion, numbness, pain syndromes, infection, and longer operative times and hospital stays. Prospective studies following patients for years after surgery have documented persistent deficits in shoulder strength and function in women who undergo the full dissection compared with those who receive sentinel biopsy alone. If equivalent survival can be achieved without those complications, the argument for routine full dissection in chemotherapy responders weakens considerably — and the Pittsburgh data suggest that even some patients with residual disease in the marked node may fare just as well with less surgery when combined with appropriate radiation and systemic therapy.

The findings arrive amid an active international effort to define exactly how far axillary de-escalation can safely go. Ongoing randomized trials, including TAXIS and the AXSANA study, are comparing less invasive nodal procedures with standard approaches in patients whose disease converts from node-positive to node-negative after chemotherapy. Practice guidelines, including those from the National Comprehensive Cancer Network, have gradually incorporated the option of omitting full dissection for selected patients with a complete response, and surveys of breast surgeons show rapidly shifting practice patterns. The present study adds real-world evidence to this landscape: in a consecutive cohort treated at a single academic center, the extent of axillary surgery simply did not determine who recurred, who survived, or how long they lived free of disease.

Important limitations temper the conclusions. The analysis was retrospective and single-institution, meaning treatment decisions were not randomized and selection bias may have influenced which patients received which operation — indeed, patients with persistent disease were far more likely to undergo full dissection, likely reflecting surgeon and patient preference for maximal treatment. The follow-up of just over three years is meaningful but not definitive for breast cancer, whose recurrences can appear a decade or more after diagnosis, and the small numbers of full dissections among patients with complete response limit statistical power. Nevertheless, the consistency of the results across both patient groups, and their alignment with randomized trial evidence accumulated over the past two decades, makes a compelling case. For the growing number of women whose lymph node disease melts away with preoperative chemotherapy, the message is increasingly clear: the most extensive operation is not the one that saves lives, and a carefully targeted, node-by-node approach may offer the same survival with a fraction of the harm.

Subject of Research: Comparison of targeted axillary dissection versus axillary lymph node dissection for survival outcomes in node-positive breast cancer patients receiving neoadjuvant chemotherapy

Article Title: Equivalent survival in targeted axillary dissection compared to axillary lymph node dissection in patients with node positive breast cancer receiving neoadjuvant chemotherapy

Article References: Hlavin, C., Balogun, Z., Lavage, D. R., Cowher, M. S., Lupinacci, K., Sabih, Q., Soran, A., Steiman, J. G., McAuliffe, P. F., & Diego, E. J. (2026). Equivalent survival in targeted axillary dissection compared to axillary lymph node dissection in patients with node positive breast cancer receiving neoadjuvant chemotherapy. Breast Cancer Research and Treatment, 219(3), Article 18. https://doi.org/10.1007/s10549-026-08078-1

Image Credits: AI Generated

DOI: 10.1007/s10549-026-08078-1

Keywords: breast cancer, neoadjuvant chemotherapy, targeted axillary dissection, axillary lymph node dissection, sentinel lymph node biopsy, axillary de-escalation, lymphedema, disease-free survival, overall survival, pathologic complete response, radioactive seed localization, surgical oncology

Triple-negative breast cancer, defined by the absence of estrogen receptor and progesterone receptor expression and the lack of HER2 amplification, accounts for roughly 10 to 15 percent of all breast cancers but carries a disproportionate share of early recurrences and deaths. Because the tumor lacks the molecular targets that make other breast cancer subtypes vulnerable to endocrine therapy or HER2-directed drugs, cytotoxic chemotherapy has remained the backbone of treatment. Historically, anthracycline-and-taxane regimens have been the standard of care, producing pathologic complete response rates of roughly 37 to 41 percent. When patients achieve a pathologic complete response, meaning no residual invasive cancer is found in the breast or lymph nodes at the time of surgery, their five-year event-free survival approaches 90 percent, compared with 57 percent for those who do not. That makes the response a powerful surrogate for cure and a critical endpoint for evaluating treatment strategies.

The trouble with anthracyclines lies in what they leave behind. Pooled data from randomized controlled trials show that patients treated with anthracycline-containing regimens face more than a five-fold higher risk of clinical cardiotoxicity, as well as sharply elevated risks of acute myeloid leukemia and myelodysplastic syndrome. Long-term follow-up studies in breast cancer survivors have documented heart failure, arrhythmias, and secondary blood cancers years or decades after the original diagnosis. For young women facing the prospect of decades of survival after successful breast cancer treatment, these late effects are not trivial side effects; they are life-altering or life-shortening complications in their own right. Reducing or eliminating anthracycline exposure without sacrificing cancer control has therefore become one of the most consequential questions in early breast cancer management.

At the same time, the treatment landscape has been transformed by two major developments. The first is the incorporation of carboplatin, a platinum chemotherapy agent, into neoadjuvant regimens. Trials such as GeparSixto, CALGB 40603, and BrighTNess demonstrated that adding carboplatin increases pathologic complete response rates in triple-negative disease, although often at the cost of substantially more hematologic toxicity, treatment delays, and dose reductions. The second development is immunotherapy. The landmark KEYNOTE-522 trial established perioperative pembrolizumab, an antibody that blocks the PD-1 immune checkpoint, combined with neoadjuvant chemotherapy as the new standard of care for stage II and III disease, improving both pathologic complete response and overall survival. Yet real-world experience with that regimen has revealed higher-than-anticipated immune-related adverse events, frequent discontinuation, and dose reductions, raising concerns about how much drug burden patients can realistically tolerate.

Against this shifting backdrop, a research team led by investigators at the University of Iowa and the University of Wisconsin, working with the Greater Plains Collaborative, a PCORnet clinical research network spanning ten medical centers across nine states, asked a deceptively simple question: in actual clinical practice, does adding anthracyclines to carboplatin plus taxane chemotherapy improve outcomes? They compared two regimens among women with stage I to III triple-negative breast cancer diagnosed between 2012 and 2024. The first, abbreviated CbT, consisted of carboplatin plus a taxane. The second, AC-CbT, added doxorubicin plus cyclophosphamide, the classic anthracycline combination. The primary outcome was pathologic complete response as recorded in hospital cancer registries by treating physicians, supplemented where necessary by comparisons of pre-treatment clinical staging and post-surgical pathologic staging.

The results were striking in their clarity. Among the 878 women analyzed, 41.2 percent received the anthracycline-free CbT regimen and 58.8 percent received AC-CbT. Half of the entire cohort achieved a pathologic complete response. On the surface, the anthracycline group appeared to fare slightly better, with response rates of 51.9 percent versus 47.2 percent for CbT, but this difference was not statistically significant. More importantly, after multivariable adjustment using inverse probability weighting, accounting for age, stage, grade, race, body mass index, comorbidity, treatment site, and pembrolizumab use, the addition of anthracyclines conferred no meaningful advantage, with an adjusted odds ratio of 1.05 and a confidence interval spanning 0.69 to 1.59. Sensitivity analyses that reclassified ambiguous response data or excluded those cases entirely produced the same conclusion.

What did predict response? Pembrolizumab use nearly doubled the odds of pathologic complete response, with an adjusted odds ratio of 1.97. Higher-grade tumors were more likely to respond, paradoxically, with grade 3 disease carrying nearly twice the odds of grade 1 or 2 tumors, a pattern consistent with the principle that the most biologically aggressive cancers are often the most sensitive to chemotherapy. Lower stage predicted higher response, as expected, and women diagnosed between ages 40 and 49 were roughly twice as likely to respond as those diagnosed at 60 or older, a finding the investigators probed extensively with post hoc and machine-learning analyses without uncovering an obvious explanation. Notably, an interaction analysis showed no evidence that anthracyclines mattered more or less depending on whether pembrolizumab was given, suggesting the anthracycline question remains unresolved in both the immunotherapy era and outside it.

The study also documents a dramatic practice transformation. Among all 2,413 triple-negative breast cancer patients in the underlying dataset, use of any carboplatin-containing regimen rose from 7.1 percent in 2012 to 72.8 percent in 2024. Pembrolizumab uptake was swift following the 2021 publication of KEYNOTE-522 results, and by the end of the study period, 46 percent of the analytic cohort had received it, concentrated overwhelmingly in the anthracycline-containing group. Interestingly, the data reveal how oncologists tailor care in the real world: older patients and those with comorbidities were more likely to forgo anthracyclines, while those with stage III, more aggressive disease were more likely to receive all four cytotoxic drug classes. Nearly a third of patients received combinations that had never appeared in clinical guidelines, reflecting deliberate individualized risk-benefit balancing rather than rigid protocol adherence.

Perhaps most provocative is the finding that carboplatin has penetrated into stage I disease, a population excluded from KEYNOTE-522 and still recommended anthracycline-taxane therapy by National Comprehensive Cancer Network guidelines. Among all stage I patients in the dataset, 19.4 percent received carboplatin, rising from 3.4 percent in 2012 to 41.7 percent in 2024. Within the analytic cohort, stage I patients showed similar response rates with or without anthracyclines. This off-guideline adoption finds precedent in the adjuvant PATTERN trial, in which carboplatin plus paclitaxel matched anthracycline-based therapy in five-year overall survival, with three-quarters of enrolled patients having node-negative disease.

The investigators are careful to acknowledge limitations. As an observational study relying on electronic health records and registry data, it cannot exclude unmeasured confounding, and variables such as performance status, BRCA mutation status, treatment toxicity, adherence, and relative dose intensity were unavailable. Lower delivered doses in the four-drug regimen could theoretically explain the lack of anthracycline benefit, although the authors argue that real-world tolerability is itself a legitimate measure of a regimen’s worth. The cohort also lacked racial diversity, and a notable fraction of responses were classified as “not otherwise specified,” though sensitivity analyses confirmed the robustness of the central finding.

Even with those caveats, the study represents, to the authors’ knowledge, the largest real-world analysis of triple-negative breast cancer spanning the immunotherapy era, and it provides the strongest real-world evidence yet that anthracyclines may not earn their place alongside carboplatin-based chemoimmunotherapy. Ongoing randomized trials, most notably the SCARLET trial evaluating anthracycline-free chemoimmunotherapy against the full KEYNOTE-522 regimen, will determine whether anthracycline omission can be definitively declared noninferior. Until then, this research shifts the burden of proof: the question is no longer whether patients can safely be spared anthracyclines, but whether the drugs still have anything left to offer.

Subject of Research: Anthracycline-containing versus anthracycline-free carboplatin-based regimens in early-stage triple-negative breast cancer: real-world outcomes

Article Title: Anthracycline-containing versus anthracycline-free carboplatin-based regimens in early-stage triple-negative breast cancer: real-world outcomes

Article References: Kroll, M. R., Schroeder, M. C., Neuner, J. M., Viyyuri, B. R., Ravindra, A., McDougall, D., Chapman, C. G., Fleege, N. M. G., Chrischilles, E. A., Song, X., & Phadke, S. (2026). Anthracycline-containing versus anthracycline-free carboplatin-based regimens in early-stage triple-negative breast cancer: real-world outcomes. Breast Cancer Research and Treatment, 219(2), Article 7. https://doi.org/10.1007/s10549-026-08071-8

Image Credits: AI Generated

DOI: 10.1007/s10549-026-08071-8

Keywords: Anthracycline-containing, versus, anthracycline-free, carboplatin-based, regimens, early-stage, triple-negative, breast, cancer, real-world, outcomes, scientific research