Although the use of oral contraceptives (OC) is widespread, the impact of OC usage on carcinogenesis is not well recognized. A recent study from the Agency for Healthcare Research and Quality noted a need to better understand the consistency of OC usage and cancer links across subpopulations, particularly smokers and obese women. To see if lifestyle factors influenced the relationship between the length of OC usage and the risk of certain malignancies was the objective of this research.

The prospective NIH-AARP Diet and Health Study (enrolled 1995-1996, followed through 2011), which used population-based recruiting of AARP members in six states and two metropolitan regions. At least 100,000 women who reported OC usage at enrolment were included in all analyses. During the course of the study, researchers discovered 1241 instances of ovarian cancer, 2337 cases of endometrial cancer, 11,114 cases of breast cancer, and 3507 cases of colorectal cancer. Between September 2016 and April 2017, data analysis was carried out. 


At enrolment, the analytic population ranged in age from 50 to 71 years and was predominantly white (91%) and postmenopausal (96%). For ovarian cancer, the risk reductions associated with OC usage increased with time (long-term OC use [10 years] HR, 0.60; 95% CI, 0.47-0.76; P.001 for trend) and were consistent across modifiable lifestyle variables. Long-term OC usage reduced the risk of endometrial cancer (HR, 0.66; 95% CI, 0.56-0.78; P.001 for trend); the most substantial reductions were among long-term OC users who were smokers (HR, 0.47; 95% CI, 0.25-0.88), had obese BMIs (0.36; 95% CI, 0.25-0.52), and exercised seldom (HR, 0.40; 95% CI, 0.29-0.56). The majority of the studies found no link between OC usage and breast or colorectal cancer.