Rosenberg L, Palmer J R, Kaufman D W, Strom B L, Schottenfeld D, Shapiro S
Slone Epidemiology Unit, Boston University School of Medicine, MA 02146.
Am J Epidemiol. 1988 May;127(5):981-9. doi: 10.1093/oxfordjournals.aje.a114901.
The authors evaluated whether an induced or spontaneous abortion during the first six months of gestation, particularly if it occurs before the first term pregnancy, increases the risk of breast cancer. Data from a case-control study of women under 70 years of age were used: 3,200 cases of breast cancer were compared with 4,844 controls with nonmalignant nongynecologic conditions. Among both nulliparous and parous women, the risk of breast cancer was not related to the number of induced or spontaneous abortions. After allowance for all identified potential confounding factors, the estimated relative risk for nulliparous women with an induced abortion relative to those who had never been pregnant was 1.3 (95% confidence interval (CI) 0.8-2.2), and for spontaneous abortion, the corresponding estimate was 0.9 (95% CI 0.5-1.5). Among parous women, the estimated relative risks were 1.2 (95% CI 0.9-1.6) for an induced abortion and 0.9 (95% CI 0.8-1.0) for a spontaneous abortion, relative to never having had an abortion of any type. The time of the abortion had little effect: The relative risk estimates were 0.9 (95% CI 0.5-1.4) for induced abortion before the first term birth, 1.4 (95% CI 1.0-1.9) for induced abortion first occurring after the first term birth, 0.9 (95% CI 0.7-1.2) for spontaneous abortion before the first term birth, and 0.9 (95% CI 0.7-1.0) for spontaneous abortion first occurring after the first term birth. Similar results were evident for women under age 40, among whom the frequency of induced abortion was relatively high. These data suggest that the risk of breast cancer is not materially affected by abortion, regardless of whether it occurs before or after the first term birth.
作者评估了妊娠前六个月进行人工流产或自然流产，尤其是在首次足月妊娠之前发生流产，是否会增加患乳腺癌的风险。研究使用了一项针对70岁以下女性的病例对照研究数据：将3200例乳腺癌病例与4844例患有非恶性非妇科疾病的对照进行比较。在未生育和已生育的女性中，乳腺癌风险与人工流产或自然流产的次数均无关。在考虑了所有已识别的潜在混杂因素后，未生育女性人工流产相对于从未怀孕女性的估计相对风险为1.3（95%置信区间（CI）0.8 - 2.2），自然流产的相应估计值为0.9（95%CI 0.5 - 1.5）。在已生育女性中，相对于从未进行过任何类型流产的女性，人工流产的估计相对风险为1.2（95%CI 0.9 - 1.6），自然流产为0.9（95%CI 0.8 - 1.0）。流产时间影响不大：首次足月分娩前人工流产的相对风险估计值为0.9（95%CI 0.5 - 1.4），首次足月分娩后首次发生人工流产的相对风险为1.4（95%CI 1.0 - 1.9），首次足月分娩前自然流产为0.9（95%CI 0.7 - 1.2），首次足月分娩后首次发生自然流产为0.9（95%CI 0.7 - 1.0）。40岁以下女性也有类似结果，她们的人工流产频率相对较高。这些数据表明，无论流产发生在首次足月分娩之前还是之后，乳腺癌风险都不会受到实质性影响。
