乳腺癌发病率在不同族群间存在差异，欧美国家白人女性患病风险整体高于亚洲及非洲女性。不过英国一项大规模研究显示，这种差异在很大程度上源自生活方式，遗传因素并非主因。
英国牛津大学等机构研究人员在新一期《英国癌症杂志》上报告说，他们对英格兰地区超过100万名年龄在50至64岁之间的女性进行了健康调查，其中有近6000名南亚裔女性和近5000名非洲裔女性，研究人员通过调查问卷、查阅医疗记录等方式对她们的生活习惯、新生儿喂养方式及乳腺癌患病情况进行了分析。
结果发现，白人女性患乳腺癌的几率最高，与之相比，南亚裔女性的患病几率要低18％，非洲裔女性的患病几率要低15％。进一步分析显示，在影响患病风险的因素中，生活方式所占比重远大于基因差异。
具体来看，白人女性中仅有23％报告说不饮酒，而南亚裔和非洲裔女性有75％和38％不饮酒；白人女性的母乳喂养率不足七成，而另外两者这一比例均超过八成；白人女性使用激素替代疗法缓解更年期综合征的比例也更高。如果在计算中去除这些风险因素的影响，不同族群女性患乳腺癌的风险则相差不多。
研究人员说，这项研究说明，乳腺癌患病风险在“很大程度上”与生活方式密切相关，这再次提醒女性坚持健康生活方式对于降低乳腺癌风险的重要性，比如应注意膳食平衡、减少饮酒、适量运动和控制体重等。
Ethnic differences in breast cancer incidence in England are due to differences in known risk factors for the disease: prospective study
background: In the United Kingdom, breast cancer incidence is lower in South Asian and Black women than in White women, but the extent to which this is due to known risk factors is unknown. In a large prospective study, we describe breast cancer incidence by ethnicity, before and after adjustment for known risk factors for the disease.
methods: Women were recruited into the Million Women Study in 1996–2001, when information on reproductive and lifestyle factors known to influence the risk of breast cancer was obtained. Ethnicity was determined from study questionnaires and hospital admission data. Cox regression models were used to calculate adjusted relative risks (RR) for incident breast cancer in South Asians and Blacks compared with Whites.
results: Analyses included 5877 South Asian, 4919 Black, and 1 038 144 White women in England. The prevalence of 8 out of the 9 risk factors for breast cancer examined, differed substantially by ethnicity (P<0.001 for each), such that South Asian and Black women were at a lower risk of the disease than White women. During 12.2 years of follow-up incident breast cancer occurred in 217 South Asians, 180 Blacks, and 45 191 Whites. As expected, breast cancer incidence was lower in South Asians (RR=0.82, 95% CI 0.72–0.94) and Blacks (RR=0.85, 0.73–0.98) than in Whites when the analyses were adjusted only for age and region of residence. However, after additional adjustment for the known risk factors for the disease, breast cancer incidence was similar to that of Whites, both in South Asians (0.95, 0.83–1.09) and in Blacks (0.91, 0.78–1.05).
conclusion: South Asian and Black women in England have lower incidence rates of breast cancer than White women, but this is largely, if not wholly, because of differences in known risk factors for the disease.
Keywords: breast cancer incidence; ethnicity; breast cancer risk factors
