TITLE: Oral contraceptive use and early abortion as risk factors for breast cancer in young women.

AUTHORS: Pike MC; Henderson BE; Casagrande JT; Rosario I; Gray GE

SOURCE: Br J Cancer 1981 Jan;43(1):72-6 CITATION IDS:PMID: 7459241 UI: 81110289

ABSTRACT: A case-control study was conducted in Los Angeles County, California, of 163 very young breast-cancer cases (all aged 32 or less at diagnosis) to investigate the role, if any, of oral contraceptives (OC) in the development of the disease. OC use before first full-term pregnancy (FFTP) was associated with an elevated risk, which increased with duration of OC use (relative risk approximately 2.2 at 6 years of use, P < 0.01). This increased risk could not be explained by other risk factors. OC use after FFTP was not associated with any change in risk. A first-trimester abortion before FFTP, whether spontaneous or induced, was associated with a 2.4-fold increase in breast-cancer risk (P < 0.005).