Menstrual Factors, Reproductive History and Liver Cancer Risk: Findings from a Prospective Cohort Study in Chinese Women

Background: Many studies suggested that menstrual and repro-ductive factors affected the gender disparity in liver carcinogenesis, but the results were inconsistent. Moreover, there are few studies in Asian populations. Therefore, our study was to explore the asso-ciation of menstrual and reproductive factors on liver cancer risk in Chinese women.Methods: 72,807 women were recruited in 1996 to 2000 and followed until the end of 2016 in Shanghai, China. Cox regression models were used to estimate HRs and 95% confidence intervals (CIs) for the association of menstrual and reproductive factors with liver cancer.Results: 258 liver cancer cases were identified during 1,269,531 person-years of follow-up. In premenopausal and postmenopausal women, hormone replacement therapy (HRT) and injective contraceptives were positively associated with liver cancer risk respectively (HR, 1.23, 95% CI, 1.15-1.30; HR, 1.23, 95% CI, 1.17-1.30; HR, 1.07, 95% CI, 1.05-1.10; HR, 1.08, 95% CI, 1.05-1.11), while older age at menopause, longer reproduc-tive period and fewer live births were associated with reduced risk, especially among postmenopausal women (Ptrend < 0.05). In addition, liver cancer risk was elevated in postmenopausal women who received hysterectomy (HR, 1.07; 95% CI, 1.04- 1.11), oophorectomy (HR, 1.05; 95% CI, 1.01-1.10) or oral contraceptives (HR, 1.06; 95% CI, 1.03-1.08). No association was found between age at menarche and liver cancer risk. Similar results were observed when excluding participants with less than follow-up years.Conclusions: The findings suggested that female sex hormones could play significant roles in liver carcinogenesis. Impact: Our study was the first population-based cohort to provide epidemiology evidence of menstrual and reproductive factors on liver cancer risk in Chinese women.

Automated summary

This study revealed that menstrual and reproductive factors significantly impact liver cancer risk in Chinese women. Hormone replacement therapy and injective contraceptives were positively associated with liver cancer risk in postmenopausal women, while older age at menopause, longer reproductive period, and fewer live births were linked to reduced risk.