Melbye M, Wohlfahrt J, Olsen J H, Frisch M, Westergaard T, Helweg-Larsen K, Andersen P K
Afdeling for epidemiologisk forskning, Statens Serum Instititut, København.
Ugeskr Laeger. 1998 Aug 31;160(36):5178-82.
It has been hypothesized that an interrupted pregnancy might increase the risk of breast cancer, because proliferation of breast cells will take place without the protective effect of subsequent differentiation. In a cohort of 1.5 million women (28.5 million person-years) we identified 370,715 induced abortions in 280,965 women (2.7 million person-years) and 10,246 women with breast cancer. After adjustment for other risk factors, induced abortion was not associated with the risk of breast cancer (relative risk: 1.00; 95 percent confidence interval 0.94 to 1.06). However, the relative risk of breast cancer increased with increasing gestational age of the most recently induced abortion: < 7 weeks: 0.81; 7 to 8 weeks; 1.01; 9 to 10 weeks: 1 (reference); 11 to 12 weeks: 1.12; 13 to 14 weeks: 1.13; 15 to 18 weeks: 1.23; > 18 weeks: 1.89; P(trend) = 0.016. On a population basis, induced abortion was not associated with an increased risk of breast cancer. An increase was only seen for the special group of late second trimester abortions, but this finding was based on small numbers.
据推测，中断妊娠可能会增加患乳腺癌的风险，因为乳腺细胞的增殖会在没有后续分化的保护作用下发生。在一个由150万名女性组成的队列（2850万人年）中，我们在280965名女性（270万人年）中识别出370715例人工流产，以及10246名乳腺癌患者。在对其他风险因素进行调整后，人工流产与患乳腺癌的风险无关（相对风险：1.00；95%置信区间0.94至1.06）。然而，乳腺癌的相对风险随着最近一次人工流产的孕周增加而增加：<7周：0.81；7至8周：1.01；9至10周：1（参照值）；11至12周：1.12；13至14周：1.13；15至18周：1.23；>18周：1.89；P（趋势）=0.016。从总体人群来看，人工流产与患乳腺癌风险增加无关。仅在孕中期晚期人工流产这一特殊群体中发现风险有所增加，但这一发现基于的样本量较小。
