Pike M C, Henderson B E, Casagrande J T, Rosario I, Gray G E
Br J Cancer. 1981 Jan;43(1):72-6. doi: 10.1038/bjc.1981.10.
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).
在加利福尼亚州洛杉矶县开展了一项病例对照研究，研究对象为163例非常年轻的乳腺癌患者（确诊时年龄均在32岁及以下），以调查口服避孕药（OC）在该疾病发生过程中是否起作用。首次足月妊娠（FFTP）前使用OC与风险升高相关，且风险随OC使用时间延长而增加（使用6年时相对风险约为2.2，P<0.01）。这种风险增加无法用其他风险因素来解释。FFTP后使用OC与风险的任何变化均无关联。FFTP前的孕早期流产，无论是自然流产还是人工流产，均与乳腺癌风险增加2.4倍相关（P<0.005）。
