Early menopause carries heightened risk of lung cancer in smokers

Women who experience early menopause appear to be at increased risk of developing lung cancer, but this association is limited to smokers, according to the results of a meta-analysis.

Researchers accessed multiple online databases for studies investigating the potential effect of early and late menopause on lung cancer risk. A total of 28 studies met the eligibility criteria. Of these, 26 were included in the meta-analysis of age at menopause (lowest vs highest), 11 of early menopause (≤45 vs ≥50/51 years or middle), six of late menopause (≥55 vs <50 years or middle), and six of continuous data (per additional year).

Estimated using a random-effects, pooled data showed that early menopause contributed to an increased risk of lung cancer in both cohort studies (relative risk [RR], 1.26, 95 percent confidence interval [CI], 1.10–1.41; n=6) and case-control studies (odds ratio [OR], 1.38, 95 percent CI, 1.11–1.66; n=5).

Three large cohort studies showed that the risk increase associated with early menopause was pronounced among smokers (RR, 1.38, 95 percent CI, 1.10–1.66) but not among nonsmokers (RR, 1.02, 95 percent CI, 0.63–1.40).

Four case-control studies also showed an association between late menopause and lung cancer risk (OR, 1.29, 95 percent CI, 1.08–1.51). However, this risk increase was observed among nonsmokers (OR, 1.35, 95 percent CI, 1.11–1.59) but not among smokers (OR, 1.05, 95 percent CI, 0.75–1.36).

Further prospective cohort studies should be conducted to validate the association between late menopause (≥55 years) and lung cancer risk among nonsmokers.