Secondhand smoke exposure avoidance

Avoid

2 studies · 1 recommendation

Last updated: February 15, 2026

Secondhand smoke exposure avoidance – Breast Cancer

Avoid2 studies

Avoiding secondhand smoke reduces breast cancer risk, especially with prolonged exposure

Across 2 studies—a population-based case-control study (244 cases, 1,032 controls) and a meta-analysis of up to 31 studies—passive smoke exposure consistently increases breast cancer incidence. Women exposed to secondhand smoke equivalent to 2 hours daily for 25 years faced a 3.2-fold increased risk (OR 3.2, 95% CI 1.6–6.3) compared to completely unexposed women. The meta-analysis of 11 prospective studies confirmed a 7% elevated risk (SRR 1.07, 95% CI 1.02–1.13) with near-zero heterogeneity (I² = 1%), while 20 retrospective studies showed a 30% increase (SRR 1.30, 95% CI 1.10–1.54). The dose-response pattern and consistency across study designs strengthen the case for minimizing all secondhand smoke exposure as a modifiable breast cancer prevention strategy.

Evidence

Relation of Breast Cancer with Passive and Active Exposure to Tobacco Smoke

Authors: Bemstein, Martine, Héritier, Stéphane, Khatchatrian, Naīra, Morabia, Alfredo

Published: August 2, 2017

In this population-based case-control study (244 cases, 1,032 controls), passive smoke exposure equivalent to 2 hours per day for 25 years yielded an adjusted odds ratio of 3.2 (95% CI 1.6-6.3) for breast cancer compared to women completely unexposed to both active and passive smoke. Lifetime history of passive smoking was recorded year by year from age 10 to interview date. The analysis adjusted for known or postulated breast cancer risk factors including alcohol consumption and saturated fat intake, with no evidence of strong selection, detection, or recall biases.

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Active and passive smoking and risk of breast cancer : a meta-analysis

Authors: Autier, Philippe, Boniol, Mathieu, Boyle, Peter, Macacu, Alina

Published: January 1, 2015

Meta-analysis of 11 prospective studies found ever passive smoking associated with an SRR of 1.07 (95% CI 1.02-1.13) for breast cancer with minimal heterogeneity (I² = 1%). In 20 retrospective studies, the SRR was 1.30 (95% CI 1.10-1.54) with high heterogeneity (I² = 74%). The prospective estimate, with near-zero heterogeneity, provides robust evidence of a statistically significant association between passive smoking exposure and increased breast cancer incidence.

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