Household secondhand smoke exposure and lung cancer risk among never-smoking women: a literature review.
Lung cancer in never-smoking women is a growing global public health concern. Never-smokers account for approximately 25% of all lung cancer cases worldwide, with age-standardised incidence rates higher in never-smoking women than men. Household secondhand smoke (SHS) is a major preventable environmental risk factor, and chronic exposure is consistently associated with a 20-30% increase in lung cancer risk. The risk of lung cancer among never-smoking women related to SHS is multifactorial: carcinogen-induced DNA damage and oxidative stress, genetic susceptibility amplified by polygenic risk scores, reproductive and hormonal modifiers, co-exposure to indoor air pollutants from solid‑fuel combustion, as well as regional and sociodemographic disparities. The risk is greatest in countries with a high prevalence of male smoking, poor indoor ventilation, and limited enforcement of smoke-free policies, particularly in East and South Asia. Through a narrative review of 21 studies published before March 2026, the biological and epidemiological basis for SHS-associated lung cancer in never-smoking women is examined. The results call for urgent public health measures (smoke-free home policies, indoor air pollution control) and long-term studies, multifactorial risk modelling, and evaluating interventions to reduce the global SHS-attributable lung cancer burden in this population.