Oral Contraceptives and Breast Cancer: Age-Specific Differences in theRelationship between Oral Contraceptive Use and Breast Cancer

摘要

There is some support for the hypothesis that an oral contraceptive user's riskof breast cancer could vary with age. Certain risk factors for breast cancer, including parity, marital status, race, and birthplace alter breast cancer risk in opposite directions, depending on the age that the breast cancer is diagnosed. Analyses by age indicate, however, that women with high parity who are younger than about age 35 actually have an increased risk of breast cancer compared with women of low parity at the same ages. Once a woman becomes 35 to 40 years of age, parity confers the well-described protection against breast cancer. To study the hypothesis that there may be age-specific differences in the oral contraceptive breast cancer relationship, a study reexamined data from the Cancer and Steroid Hormone Study. The present analysis examined this hypothesis with the specific intent of examining whether age effects in the OC-breast cancer relationship might be similar to age-effects seen in the parity-breast cancer relationship.