Harris N V, Weiss N S, Francis A M, Polissar L
Am J Epidemiol. 1982 Oct;116(4):643-51. doi: 10.1093/oxfordjournals.aje.a113447.
A total of 112 white females residents of King County, Washington, aged 35-54 years, who had received a first diagnosis of invasive breast cancer between July 1977 add August 1978, were investigated concerning prior use of oral contraceptives. Their responses were compared with those of a random sample of 469 demographically comparable women from the same population. Overall, oral contraceptive use in cases and controls was similar. However, use of oral contraceptives in preparous women was more common among cases than controls, with the estimated risk of breast cancer associated with such use being 2.2 times that of nonusers (90% confidence interval = 1.1-4.6). This relationship could be explained only in part by the effect of oral contraceptives in postponing or preventing childbirth. The association of breast cancer with use of oral contraceptives prior to ever giving birth has been observed in three studies, including this one, suggesting that the susceptibility of breast tissue to hormonal factors that influence the development of malignancy may be altered by having been exposed to the events of pregnancy.
对华盛顿州金县112名年龄在35至54岁之间的白人女性居民进行了调查，这些女性在1977年7月至1978年8月期间首次被诊断为浸润性乳腺癌，调查内容为她们此前使用口服避孕药的情况。将她们的回答与从同一人群中随机抽取的469名人口统计学特征相似的女性的回答进行了比较。总体而言，病例组和对照组中口服避孕药的使用情况相似。然而，未生育女性中使用口服避孕药的情况在病例组中比对照组更为常见，与这种使用相关的乳腺癌估计风险是非使用者的2.2倍（90%置信区间 = 1.1 - 4.6）。这种关系只能部分地通过口服避孕药在推迟或预防分娩方面的作用来解释。包括本研究在内的三项研究均观察到乳腺癌与首次生育前使用口服避孕药之间的关联，这表明乳腺组织对影响恶性肿瘤发展的激素因素的易感性可能会因经历过怀孕而发生改变。
