Five-Year Survival of Women with Breast Cancer According to Prior Use of Oral Contraceptives

More than 80% of US women have used oral contraceptives (OCs) at some time during their lives. Between the ages of 15 and 54, the breast is the leading site for cancer among women, and breast cancer is the leading cause of death from cancer. We examined the relationship between the survival of 4197 women diagnosed with primary breast cancer between December 1, 1980, and December 31, 1982, and their prior use of OCs. We used interview data from the Cancer and Steroid Hormone Study and survival information from the Surveillance, Epidemiology, and End Results program. In general, although the differences were not statistically significant, Kaplan-Meier estimates suggested that survival was slightly better for women who had used OCs than for never-users. Duration of OC use, age at first use, and exclusive use of specific OC formulations were not related to survival. However, survival appeared to increase with increasing time between diagnosis and first or last OC use. Women with at least 20 years latency or 15 years recency had an 83% probability of surviving five years (95% CL: 78, 88), whereas women with the shortest intervals had a 77% probability of surviving five years (95% CL: 72, 83). Women who had never used OCs had survival rates consistent with the survival experience for all users combined. OC use did not appear to have an adverse effect on the long-term risk of death from breast cancer.