Williams A O, Chung E B, Agbata A, Jackson M A
Br J Cancer. 1975 Apr;31(4):485-91. doi: 10.1038/bjc.1975.88.
Forty Africans from Nigeria and 89 American negroes with colorectal polyps were analysed by age, sex and type of polyp. The Nigerians were much the younger group (mostly under 20 years of age, whereas most of the American negroes were over 50) and far fewer of their polyps were truly neoplastic (7.5% compared with 87% of the Americans). These differences may be partly due to the American negro population being older than the Nigerian, and partly to environmental factors like those previously postulated to account for the difference in colon cancer incidence between these populations.
对40名来自尼日利亚的非洲人和89名患有结肠直肠息肉的美国黑人进行了年龄、性别和息肉类型分析。尼日利亚人是年轻得多的群体（大多在20岁以下，而大多数美国黑人超过50岁），他们真正具有肿瘤性的息肉要少得多（7.5%，而美国人是87%）。这些差异可能部分归因于美国黑人人口比尼日利亚人年龄大，部分归因于环境因素，如先前假定的那些用来解释这些人群结肠癌发病率差异的因素。
