ASPO Abstracts

Hormonal and Reproductive Risk Factors for First and Second Primary Ovarian Cancer in a Cohort Enriched for Increased Familial Risk, the Breast Cancer Family Registry

Authors: Ferris JS, Terry MB, Andrulis IL, Buys SS, Daly MB, John EM, Hopper JL, Genkinger JM

Category: Lifestyles Behavior, Energy Balance & Chemoprevention
Conference Year: 2019

Abstract Body:
Purpose: Developing a second primary cancer is one of the most severe sequelae of a cancer diagnosis and limited research has been done to assess risk factors for second primary ovarian cancer following a breast cancer diagnosis (BR-OV). Being able to identify potentially modifiable risk factors for second primary cancers is critical for cancer survivors and women at increased risk of breast and ovarian cancer; therefore, we evaluated the association between hormonal and reproductive factors and risk of BR-OV and first primary ovarian cancer (OV).Methods: Using data from the Breast Cancer Family Registry (BCFR) Cohort, we conducted a cohort study to evaluate the association between oral contraceptive (OC) use, number of full-term (FT) pregnancies, and breastfeeding and risk of BR-OV and OV using Cox Proportional Hazards models. We evaluated effect measure modification by predicted lifetime familial risk of breast or ovarian cancer estimated from pedigree data by the program BOADICEA.Results: There was no association between OC use and risk of BR-OV (HR=1.07, 95% CI: 0.51, 2.25). For women without breast cancer, OC use was marginally associated with a lower risk of OV (HR=0.59, 95% CI: 0.34, 1.00); however, this association was stronger in women with a lifetime familial risk of breast or ovarian cancer of 20% or higher (high risk) (HR=0.33, 95% CI: 0.13, 0.86). Having two or more FT pregnancies was associated with a lower risk of BR-OV (HR=0.47, 95% CI: 0.22, 0.97) but was not associated with OV. There was no association between breastfeeding and either BR-OV or OV.Conclusion: OC use may have a different effect on ovarian cancer risk depending on whether a woman has a previous diagnosis of breast cancer, and on her underlying familial risk of breast or ovarian cancer.

Keywords: Second cancerOvarian CancerBreast CancerOral contraceptivesParity