Parazzini F, La Vecchia C, Negri E, Fedele L, Balotta F
Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
Am J Obstet Gynecol. 1991 Feb;164(2):522-7. doi: 10.1016/s0002-9378(11)80012-8.
The role of reproductive factors in endometrial cancer risk has been analyzed in a case-control study conducted since 1983 in the greater Milan area on 568 women (cases) with histologically confirmed endometrial cancer and 1925 women (controls) who were admitted for acute, nonmalignant, hormonal, gynecologic conditions to hospitals that cover a comparable catchment area. Compared with nulliparous women, parous women had a 30% lower risk of endometrial cancer, but there was no evidence of a decline in risk with increasing number of births. The risk of the disease decreased with number of spontaneous or induced abortions; the multivariate relative risk estimates were, compared respectively with no spontaneous or induced abortions, 0.5 for women with two or more spontaneous abortions and 0.3 for women with two or more induced abortions; both trends in risk were statistically significant. When parous women only were considered, no association emerged between endometrial cancer and age at first birth, but the risk decreased with increasing age at last birth: compared with women whose last birth occurred before age 25, the relative risk was 0.5 for women who were greater than or equal to 35 years old at last birth, and the multivariate trend in risk was statistically significant. For most of the reproductive factors that were considered, the risk estimates tended to be greater at younger age or among premenopausal women and to flatten off in subsequent strata of age. An association between endometrial cancer and age at first birth was observed in women who were less than or equal to 49 years old, but not in older groups. The observation that later age at last birth as well as later first birth in younger women decreases the risk of endometrial cancer suggests a short-term protective effect of pregnancy. This finding is consistent with a late-stage (promotional) effect of reproductive factors on endometrial carcinogenesis.
1983年以来，在大米兰地区开展了一项病例对照研究，分析生殖因素在子宫内膜癌风险中的作用。该研究涉及568名经组织学确诊为子宫内膜癌的女性（病例组）和1925名因急性、非恶性、激素相关妇科疾病入住覆盖类似集水区医院的女性（对照组）。与未生育女性相比，生育过的女性患子宫内膜癌的风险低30%，但没有证据表明随着生育次数增加风险会降低。疾病风险随着自然流产或人工流产次数的增加而降低；多变量相对风险估计显示，与无自然流产或人工流产的女性相比，有两次或更多次自然流产的女性为0.5，有两次或更多次人工流产的女性为0.3；两种风险趋势均具有统计学意义。仅考虑生育过的女性时，子宫内膜癌与初产年龄之间未发现关联，但风险随着末次生育年龄的增加而降低：与末次生育发生在25岁之前的女性相比，末次生育时年龄大于或等于35岁的女性相对风险为0.5，多变量风险趋势具有统计学意义。对于所考虑的大多数生殖因素，风险估计在较年轻年龄组或绝经前女性中往往更高，而在随后的年龄组中趋于平稳。在年龄小于或等于49岁的女性中观察到子宫内膜癌与初产年龄之间存在关联，但在年龄较大的组中未观察到。末次生育年龄较晚以及年轻女性初产较晚可降低子宫内膜癌风险这一观察结果表明妊娠具有短期保护作用。这一发现与生殖因素对子宫内膜癌发生的晚期（促进）作用一致。
