Abstract 2165: Parents' ages at birth and risk of hormone-related cancer among women in the California Teachers Study

Abstract

Abstract Childbearing age has increased in Western countries over the last several decades. The immediate effects of advanced parental age on the health of offspring have been extensively studied. However, few studies have examined the effect of parental age at birth on the risk of adult-onset cancer. We explored the association between parental age at birth and the risk of adult-onset hormone-related cancers (i.e., breast cancer, ovarian cancer and endometrial cancer) in the prospective California Teachers Study cohort of 133,479 female teachers and administrators. Between 1995 and 2010, 5359 women were diagnosed with breast cancer, 515 women were diagnosed with ovarian cancer, and 1110 women were diagnosed with endometrial cancer. Multivariate adjusted relative risks (RR) and 95% confidence intervals (CI) were estimated by fitting Cox proportional hazards models. After mutual adjustment for paternal age/maternal age at birth, no association was observed for maternal age at birth for any of the three types of cancer. However, compared to those born to a father whose age at his daughter's birth was 25-29 years, women born to a father under age 20 years had 35% greater risk of breast cancer (RR=1.35, 95% CI=1.03-1.76) and more than 2 times greater risk of ovarian cancer (RR=2.26, 95% CI=1.14-4.50); women born to a father whose age at childbirth was 30-34 years had 25% greater risk of endometrial cancer (RR=1.25, 95% CI=1.05-1.48) than women whose father was 25-29 years. In an interaction model, relative to daughters born to a mother younger than 25 year and a father between 25-29 years, relative risk was elevated for those born to a mother younger than 25 and a father younger than 20 years (RR=1.37, 95% CI=1.07-1.76), or to a father older than 34 years old regardless of mother's age (mother <25 or ≥25 years old; RR=1.31 and 1.12 respectively). Lower ovarian cancer risk was observed among women born to a mother ≥25 years and a father between 25-29 years (RR=0.66, 95% CI=0.48-0.90); no association was observed for endometrial cancer. These findings indicate that parental age at birth, especially paternal age at birth, may affect the adult-onset cancer risk of daughters, especially breast cancer. Citation Format: Yani Lu, Jianning Luo, Sophia Wang, Huiyan Ma, Jane Sullivan-Halley, Peggy Reynolds, Leslie Bernstein. Parents' ages at birth and risk of hormone-related cancer among women in the California Teachers Study. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2165. doi:10.1158/1538-7445.AM2014-2165