title: Oral contraceptive use and early abortion as risk factors for breast cancer in young women.
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).
mesh_terms: D000028:Abortion, Induced / Q000009:adverse effects*; D000022:Abortion, Spontaneous / Q000150:complications*; D000328:Adult; D000367:Age Factors; D001943:Breast Neoplasms / Q000139:chemically induced / Q000209:etiology* / Q000235:genetics; D003276:Contraceptives, Oral / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008572:Menarche; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012306:Risk
chemical_list: D003276:Contraceptives, Oral