Association between adolescent alcohol consumption and cigarette smoking with adult risk of breast cancer: A systematic review and meta-analysis.
TL;DR
Adolescent smoking was associated with a modest increase in breast cancer risk, whereas no clear association was observed for adolescent alcohol consumption, and the potential value of smoking prevention during adolescence is highlighted.
Abstract
Objective
Alcohol and smoking are established carcinogens; however, evidence on adolescent exposure during mammary development on breast cancer risk remains inconsistent. This study assessed the associations between adolescent alcohol intake, smoking, and adult breast cancer risk.
Methods
A systematic search of PubMed/MEDLINE (1966), Web of Science (1900), and Scopus (1970) from inception to September 2025 identified 31 eligible studies (eleven on alcohol, twenty on smoking). Pooled relative risks (RRs) with 95% confidence intervals (CIs) were estimated using random-effects models.
Results
No overall association was observed between adolescent alcohol consumption and breast cancer risk (RR = 1.11, 95% CI: 0.93, 1.33). Although alcohol initiation at ≤15 years was associated with higher risk in subgroup analyses, evidence was inconsistent. Adolescent smoking was associated with increased breast cancer risk (RR = 1.12, 95% CI: 1.05, 1.19). The certainty of evidence was very low for both exposures.
Conclusions
Adolescent smoking was associated with a modest increase in breast cancer risk, whereas no clear association was observed for adolescent alcohol consumption. These findings highlight the potential value of smoking prevention during adolescence. However, the very low certainty of evidence warrants cautious interpretation, and future prospective studies are needed to disentangle adolescent behaviours from lifetime exposures.