The association between hormone therapy and the risk of lung cancer in postmenopausal women: a 16-year nationwide population-based study.

OBJECTIVE: Although an association between hormone therapy (HT) and the risk of developing lung cancer has been reported, the results on the topic are inconsistent. Our study objective was to investigate whether postmenopausal women who undergo HT exhibit a risk of developing lung cancer.

METHODS: In this matched cohort study, we obtained the data of 38,104 postmenopausal women older than 45 years who were treated using HT between 2000 and 2015 from Taiwan's National Health Insurance Research Database, and 152,416 matched participants who were not treated using HT were enrolled as controls at a 1:4 ratio.

RESULTS: We used a Cox proportional hazards regression model to identify the risk of developing lung cancer during 16 years of follow-up, and the results indicate no significant difference in the proportion of postmenopausal women treated using HT (P = 0.129) who developed lung cancer and that of those not treated using HT (0.866% [330 of 38,104] vs 0.950% [1,449 of 152,416]). After adjustment for age and other variables, the adjusted hazard ratio was 0.886 (95% CI, 0.666-1.305, P = 0.433), indicating no association between HT and lung cancer development in postmenopausal women. In a subgroup analysis, the risk of lung cancer was significantly lower in the women who were treated using HT when the HT cumulative dosage was ≥401 mg or when the therapy duration was ≥5 years compared with in those not treated using HT; the adjusted hazard ratios were 0.633 (95% CI, 0.475-0.930; P < 0.001) and 0.532 (95% CI, 0.330-0.934; P < 0.001), respectively, after adjustment.

CONCLUSIONS: Our results indicate that HT is not associated with the risk of lung cancer development in postmenopausal women; furthermore, a higher cumulative dosage and the long-term effects of HT reduce the risk of developing lung cancer.