The scale of the problem is difficult to overstate. According to the WHO’s Global Cancer Observatory, there were 19.3 million new cancer cases and 10 million cancer deaths worldwide in 2020, and annual incidence is projected to climb to roughly 28 to 30 million by 2040 if current trends continue. Lung cancer remains the single largest contributor to cancer mortality, accounting for about one in five cancer deaths globally. While targeted therapies and immunotherapies have improved outcomes for some patients, survival rates remain persistently low in low- and middle-income countries where screening and specialized care are limited. The review’s authors contend that this clinical picture cannot be separated from the environments in which people spend their lives, and time-activity studies show that individuals spend more than 80 percent of their time indoors, making the home the primary site of chronic exposure to environmental agents that influence cancer risk.

Among indoor hazards, radon stands out as the most consistently documented housing-related carcinogen. The International Agency for Research on Cancer classifies radon as a Group 1 human carcinogen, and it is recognized worldwide as the second leading cause of lung cancer after tobacco smoking. Radon concentrations vary widely depending on geological uranium content and building characteristics, with national surveys showing especially high levels in regions such as Manitoba and New Brunswick in Canada, the Southwest of England, parts of Sweden, central Anatolia in Turkey, and Iceland. In these areas, radon levels frequently exceed the WHO reference level of 100 becquerels per cubic meter, with some households recording concentrations several times higher. Pooled case-control studies demonstrate a linear dose-response relationship between long-term radon exposure and lung cancer risk, with risk increasing by roughly 16 percent per 100 becquerels per cubic meter of chronic exposure, even below many national action levels. Importantly, the excess relative risk is evident among never-smokers as well as smokers, and radon-related lung cancers are often diagnosed at later clinical stages, contributing to high mortality.

Perhaps the most counterintuitive finding concerns energy-efficiency retrofits. Evidence from Canada, the United Kingdom, and Scandinavia shows that adding insulation or tightening building envelopes to reduce heat loss can increase indoor radon concentrations when not paired with balanced mechanical ventilation. Cross-sectional studies and natural experiments following national retrofit programs consistently demonstrate median radon increases of 20 to 50 percent in homes that were sealed without added ventilation. This creates a genuine policy dilemma: climate mitigation demands energy-efficient housing, yet poorly designed retrofits may unintentionally modify cancer risk pathways, particularly for households with limited resources to implement mitigation measures. The review argues that policies funding or mandating energy upgrades should require integrated indoor air-quality protections, including pre- and post-retrofit radon testing, installation of heat-recovery or energy-recovery ventilators, and high-efficiency particulate air filtration rated MERV-13 or higher.

Combustion-derived pollutants form a second major exposure pathway. An estimated 2.3 billion people worldwide rely on solid fuels such as wood, coal, or crop residues for household energy, exposing residents to fine particulate matter and carcinogenic compounds including polycyclic aromatic hydrocarbons and volatile organic compounds. The IARC has estimated that household use of coal for cooking or heating roughly doubles to quintuples the risk of lung cancer. In certain high-exposure settings such as Xuanwei County in China, U.S. National Cancer Institute investigators have documented far higher risks, up to a 99-fold increase in lung cancer among never-smoking women who used smoky coal compared with smokeless coal. The burden is profoundly gendered: women and children who spend more time near cooking fires bear the highest exposures and risk. Yet the review emphasizes that this is not solely a problem of low- and middle-income countries. In high-income nations, energy-insecure households may depend on wood stoves or unvented gas heaters, sustaining elevated indoor fine particulate matter levels that can exceed WHO guidelines.

Energy insecurity also operates through behavioral adaptations to thermal and financial strain. Conceptual frameworks distinguish physical, economic, and coping dimensions of the phenomenon, whereby unaffordable utility costs and poor housing efficiency compel residents to use ovens or gas stoves for space heating, block ventilation to conserve heat, or rely on portable propane heaters. These coping strategies can substantially elevate indoor concentrations of nitrogen dioxide, carbon monoxide, benzene, and fine particulate matter, intensifying exposure to carcinogenic and cardiopulmonary toxicants even in formally connected and housed settings. The review frames this behavioral dimension as clarifying how energy insecurity operates as an active exposure-shaping process rather than a passive socioeconomic backdrop.

The most striking emerging evidence concerns particle radioactivity, specifically gross beta activity, a measure of the radioactive component of ambient particulate matter. The strongest data come from the Boston Lung Cancer Survival cohort, a prospective study of 2,795 patients with histologically confirmed lung cancer treated at Massachusetts General Hospital and Dana-Farber Cancer Institute and followed from 1992 through 2017. Monthly exposure estimates were generated using an ensemble machine-learning model trained on data from the U.S. EPA RadNet monitoring network. In Cox proportional hazards models adjusted for age, sex, race, smoking status, stage, histology, and ZIP-code income, each interquartile range increase in gross beta activity was associated with a 63 percent higher hazard of death. A clear dose-response gradient emerged: compared with the lowest exposure quartile, which had a median overall survival of 46 months, hazard ratios rose progressively across quartiles, reaching 2.20 in the highest quartile, where median survival fell to 14.7 months. Critically, these associations persisted after co-adjustment for residential radon, and stronger associations were observed among patients diagnosed with early-stage disease, suggesting that continued exposure may accelerate disease progression or undermine the effectiveness of curative treatments such as surgery or radiation therapy.

Mechanistically, the review outlines how these exposures become biologically embedded. Radon progeny and radioactive particles attach to fine particulate matter and, once inhaled, are deposited deep in the respiratory tract, where they emit alpha, beta, and gamma radiation capable of producing reactive oxygen and nitrogen species. These reactive molecules inflict DNA double-strand breaks, base damage, and chromosomal aberrations, and interfere with DNA repair mechanisms. Oxidative stress also triggers lipid peroxidation and protein modification, activating oncogenic signaling cascades and inhibiting tumor suppressor pathways. In parallel, housing and energy insecurity function as chronic psychosocial stressors. Persistent financial strain, thermal discomfort, and fear of eviction or utility shutoffs repeatedly activate neuroendocrine and inflammatory stress-response systems, contributing to elevated allostatic load. Prolonged dysregulation of the hypothalamic-pituitary-adrenal axis has been linked to immune suppression, oxidative stress, and altered DNA repair, and psychoneuroimmunology research demonstrates that chronic stress can alter immune surveillance and modify the tumor microenvironment in ways that facilitate disease progression and reduce treatment responsiveness.

Social determinants amplify every one of these pathways. The literature consistently shows that lower socioeconomic status, racialized status, limited education, and unstable housing are associated with higher exposure to residential carcinogens, later stage at diagnosis, and poorer survival. Population-based studies in Canada and the United States have demonstrated that residents of lower-income neighborhoods have higher lung and cervical cancer incidence and lower survival rates across multiple cancer types, even after controlling for smoking and other individual-level risk factors. People experiencing homelessness represent an extreme manifestation of both housing and energy insecurity, facing chronic exposure to ambient air pollution, second-hand smoke, and cold stress, combined with reliance on shelters with poor ventilation, high smoking prevalence, and profound barriers to screening, continuity of care, and treatment adherence. The review also identifies a bidirectional and self-reinforcing cycle of vulnerability: a cancer diagnosis frequently brings substantial out-of-pocket costs, reduced income, and increased caregiving demands that can precipitate or worsen housing instability and difficulty affording household energy, which in turn may compromise treatment adherence and recovery. Encouragingly, randomized trials targeting food insecurity among low-income patients with cancer have shown improvements in treatment completion, quality of life, and psychological well-being, suggesting that addressing material hardship can improve cancer outcomes.

The review’s authors conclude that effective cancer control demands integration of environmental, social, and clinical strategies. They call for longitudinal multi-exposure studies that integrate radon, particle radioactivity, indoor particulate matter, ventilation rates, and filtration performance with repeated measurements before and after cancer diagnosis; affordable portable sensors to reduce exposure misclassification; equity-focused analyses capturing housing type, retrofit status, and energy poverty; and expanded research in low- and middle-income countries, where most evidence on indoor combustion originates but where baseline exposures are often highest. They also urge that national monitoring networks expand their scope to include gross beta activity and make these data publicly accessible, and that oncology clinicians counsel patients, particularly those with early-stage lung cancer, about radon testing and mitigation, kitchen exhaust ventilation, smoke-free home policies, and high-efficiency filtration. By recognizing the built environment as both a source of risk and a lever for intervention, the review argues, researchers, clinicians, and policymakers can move toward housing and energy systems that support, rather than compromise, the fight against cancer.

Subject of Research: Cancer risk and the burden of housing and energy insecurity: a scoping review

Article Title: Cancer risk and the burden of housing and energy insecurity: a scoping review

Article References: Husen, Y., Zeshan, F., Odei Boateng, M., Otoadese, D., & Boateng, G. O. (2026). Cancer risk and the burden of housing and energy insecurity: a scoping review. Frontiers in Cancer Control and Society, 4, Article 1747292. https://doi.org/10.3389/fcacs.2026.1747292

Image Credits: AI Generated

DOI: 10.3389/fcacs.2026.1747292

Keywords: Cancer, risk, burden, housing, energy, insecurity, scoping, review, scientific research