Pawlega J, Wallace R
Br J Cancer. 1980 Jun;41(6):941-5. doi: 10.1038/bjc.1980.172.
Urban/rural breast-cancer incidence ratios in the state of Iowa for 1950 and 1969-71 were contrasted with corresponding urban and rural distributions of age-at-first-birth and population nutrition, variable measured approximately 15 years before each morbidity survey and putatively related to breast-cancer incidence. Over the study interval, the decline in the urban/rural breast-cancer incidence ratio correlated better with changing nutritional patterns than with changing age-at-first-birth.
爱荷华州1950年以及1969 - 1971年的城乡乳腺癌发病率之比,与首次生育年龄和人口营养的相应城乡分布情况进行了对比。这些变量是在每次发病率调查前约15年进行测量的,并且被认为与乳腺癌发病率相关。在研究期间,城乡乳腺癌发病率之比的下降与营养模式的变化相关性更强,而非与首次生育年龄的变化。