Oral Contraceptives and Risk of Breast Cancer in Women Aged 20–54 Years

The document reports on a population-based case-control study conducted in the Netherlands, which assessed the effect of timing and duration of oral contraceptive (OC) use on the risk of breast cancer in women aged 20-54 years. The study included 918 women with breast cancer and age-matched controls. The findings indicated that long-term use of OCs (12 years or more) was associated with a relative risk (RR) of 1.3 for breast cancer, with a positive trend in risk observed with increased months of use. Notably, the risk of developing breast cancer before age 36 was higher (RR 2.1) for women who used OCs for 4 or more years compared to those with shorter use. Additionally, the risk increased for longer OC use before age 20 and recent use (within the previous 3 years) was associated with increased risk in women aged 46-54. The study concluded that 4 or more years of OC use, especially if initiated before age 20, is linked to an increased risk of early-onset breast cancer, and suggested that the excess risk might diminish as the cohort ages, but this requires further confirmation.