Negri E, La Vecchia C, Parazzini F, Savoldelli R, Gentile A, D'Avanzo B, Gramenzi A, Franceschi S
Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
Cancer Res. 1989 Dec 15;49(24 Pt 1):7158-61.
The relation between reproductive and menstrual factors and the risk of colorectal cancer was investigated in a case-control study conducted in Northern Italy on 279 women with colon cancer, 153 with rectal cancer and 386 controls admitted to hospital for a wide spectrum of acute, nonneoplastic, nondigestive disorders. Compared with nulliparous women, the relative risks (RR) of colon cancer were 1.1 for one and two births, 1.3 for three or four, and 1.1 for five or more. Corresponding values for rectal cancer were 0.9 for one, 1.1 for two, 1.4 for three or four, and 0.8 for five or more births. No significant association emerged with number of abortions, and no consistent pattern of trends for both colon and rectum cancer was observed in relation to age at first or last birth. Women whose menarche occurred at age 15 or over were at significantly lower risk of colon cancer (RR 0.5, 95% confidence interval = 0.3-0.9), and the point estimate was below unity, though nonsignificantly, for rectal cancer too (RR = 0.7). There was no relation between age at menopause, duration of menstrual cycles, and cancers of the colon and rectum. The present study produced no evidence that reproductive factors are related to colorectal cancer in this population. With this sample size, it was possible to exclude relative risks below 0.8 for colon and 0.7 for rectal cancer among multiparous women versus nulliparous ones. These findings are thus inconsistent with the epidemiological evidence on reproductive and menstrual factors and breast cancer in this and other populations, with the sole potential exception of the reduced risk of colorectal cancer among women whose menarche occurred at age 15 or over.
在意大利北部开展的一项病例对照研究中，调查了生殖和月经因素与结直肠癌风险之间的关系。该研究纳入了279例结肠癌女性患者、153例直肠癌女性患者以及386名因各种急性、非肿瘤性、非消化系统疾病入院的对照者。与未生育女性相比，生育1次和2次的女性患结肠癌的相对风险（RR）为1.1，生育3次或4次的为1.3，生育5次及以上的为1.1。直肠癌的相应数值分别为：生育1次的RR为0.9，生育2次的为1.1，生育3次或4次的为1.4，生育5次及以上的为0.8。流产次数与结直肠癌无显著关联，且未观察到结肠癌和直肠癌在首次或末次生育年龄方面的一致趋势模式。月经初潮发生在15岁及以上的女性患结肠癌的风险显著降低（RR = 0.5，95%置信区间 = 0.3 - 0.9），直肠癌的点估计值虽未达到显著水平，但也低于1（RR = 0.
