Abstract 888: Reproductive and hormonal factors and mortality risk among women with colorectal cancer in the NIH-AARP Diet and Health Study

Abstract

Abstract Introduction Women in the US have lower rates of colorectal cancer than men, which has prompted research into the role of estrogen in carcinogenesis. While use of menopausal hormone therapy (MHT) and other hormonally-related factors have been associated with lower risk of colorectal cancer (CRC), associations between these factors and colorectal cancer survival are not well defined. Methods The NIH-AARP cohort includes 566,398 AARP members (aged 50-71 years) who resided in one of six US states or two metropolitan areas and completed a mailed baseline questionnaire in 1995-1996. Among 2,053 women with incident colorectal cancer in the NIH-AARP Diet and Health Study, we examined associations of age at menarche, age at menopause, age at first birth, parity, oral contraceptive use, and menopausal hormone therapy use with overall and disease-specific mortality. Using Cox proportional hazards regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for overall and disease-specific mortality, adjusting for tumor stage and grade, treatment, years since diagnosis, body mass index, marital status, smoking status, diabetes, and physical activity. Results There were 759 deaths (332 due to CRC) over a median 7.7 years of follow-up. We observed a suggestive, but not statistically significant, lower risk of all-cause mortality among women who were 13 years or older at menarche compared to those 12 or younger (HR = 0.89, 95% CI 0.77-1.03), but no associations for age at menopause, age at first live birth, parity, or oral contraceptive use. Compared to never MHT use former MHT use was not associated with mortality risk, but we found an inverse association among current users at study entry for both all-cause mortality (HR = 0.80, 95% CI 0.67-0.94) and colorectal cancer-specific mortality (HR = 0.72, 95% CI 0.56-0.93). These associations were stronger among those who reported fewer than five years of MHT use at baseline than among those with a longer duration of use. Conclusion We found evidence of an inverse association between MHT use at study entry and all-cause and colorectal cancer-specific mortality risk. Future studies should focus on how varying usage patterns, including types of preparation used, affect tumor progression and colorectal cancer survival. Citation Format: Hannah Arem, Yikyung Park, Ashley Felix, Alice Zervoudakis, Louise A. Brinton, Charles E. Matthews, Marc J. Gunter. Reproductive and hormonal factors and mortality risk among women with colorectal cancer in the NIH-AARP Diet and Health Study. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 888. doi:10.1158/1538-7445.AM2015-888