Associations between duration of oral contraceptive use and ovarian, endometrial, breast, and colorectal cancers: modification by modifiable factors

Authors

• KA Michels
• RM Pfeiffer
• LA Brinton
• B Trabert

Abstract

In 2013, an Agency for Healthcare Research and Quality report identified a need to understand the consistency of oral contraceptive (OC) use and cancer associations across subpopulations, including smokers and obese women. We determined if these associations were modified by modifiable lifestyle characteristics (cigarette smoking, alcohol consumption, body mass index (BMI), and physical activity) using the prospective NIH-AARP Diet and Health Study (enrolled 1995-1996). All analyses included at least 100,000 women (1,241 ovarian, 2,337 endometrial, 11,114 breast, and 3,507 colorectal cancer cases identified). Lifetime duration of OC use was defined as: never/less than 1 year [reference], 1 to 4, 5 to 9, 10+ years. We estimated associations using Cox models adjusted for age, race, age at menarche, and the modifiers of interest. For ovarian cancer, OC use-associated risk reductions strengthened with duration of use (hazard ratios [HR] ranging from 0.83 to 0.60, p trend

Scientific Focus Area: Epidemiology

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