Female reproductive factors and the risk of lung cancer in postmenopausal women: a nationwide cohort study

Keun Hye Jeon,Jung Eun Yoo,Dahye Kim,Jong Ho Cho,Su-Min Jeong,Dong Wook Shin,Kyungdo Han

doi:10.1038/s41416-020-0789-7

Abstract

BackgroundReproductive factors and hormone use in postmenopausal women have been hypothesised to affect the risk of developing lung cancer, but the epidemiological evidence is inconsistent.MethodsUsing the Korean National Health Insurance System database, we identified 4,775,398 postmenopausal women older than 40 years who had undergone both cardiovascular health- and cancer screening between 1 January 2009 and 31 December 2014. Information about reproductive factors was obtained from a self-administered questionnaire. The risk of lung cancer was estimated using Cox proportional hazard regression models.ResultsDuring a median follow-up of 4.4 years, 16,556 women (15,223 non-smokers) were diagnosed with lung cancer. The risk of lung cancer was not significantly influenced by early menarche age (adjusted hazard ratio [aHR] 1.03 for menarche ≥18 vs. ≤14; 95% confidence interval [CI], 0.98–1.09) or late age at menopause (aHR 1.02 for menopause ≥55 vs. <40; 95% CI, 0.91–1.14). Furthermore, the number of children, duration of breastfeeding and use of hormone replacement therapy were not associated with the risk of lung cancer.ConclusionsNo statistically significant association was found between reproductive factors and the risk of lung cancer in postmenopausal Korean women.

Highlights

Reproductive factors and hormone use in postmenopausal women have been hypothesised to affect the risk of developing lung cancer, but the epidemiological evidence is inconsistent
Female lung cancer patients have a higher proportion of adenocarcinoma histology,[6] and a higher frequency of mutations in the epidermal growth factor receptor (EGFR)[7] than male lung cancer patients
We investigate the association between reproductive factors and the risk of lung cancer among postmenopausal women in a nationwide population cohort in Korea

Summary

Introduction

Reproductive factors and hormone use in postmenopausal women have been hypothesised to affect the risk of developing lung cancer, but the epidemiological evidence is inconsistent. Smoking is the most important risk factor, a significant portion of lung cancer in women occurs in non-smokers.[4] Global statistics estimate that 20% of lung cancer in Western populations develops in non-smokers.[1] In Korea, 38% of female non-small-cell lung cancer patients reported themselves to be non-smokers.[5] Female lung cancer patients have a higher proportion of adenocarcinoma histology,[6] and a higher frequency of mutations in the epidermal growth factor receptor (EGFR)[7] than male lung cancer patients Such sex-related differences suggest that hormonal factors might influence the development of lung cancer. A recent study revealed a sex-related difference in oestrogen receptor β nuclear expression.[8]

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Results

Conclusion