Association of obesity and ovarian cancer in a case-control study.

Data from a population-based case-control study conducted in Washington State and Utah were used to assess whether obesity is associated with an altered risk of epithelial ovarian cancer. Quetelet index, defined as weight (kg) at age 30 years divided by height (m) squared, was calculated for each woman, and the values for all subjects were divided into five categories of approximately equal size. Compared with women in the lowest category, women in the highest category had an odds ratio of 1.7 (95 per cent CI 1.1-2.7). Risks for women in the three intermediate Quetelet index categories also exceeded the risk for women in the lowest group, but to a much smaller degree. Among women with serous tumors, those in the highest Quetelet index category were at a greater than twofold excess risk (OR = 2.2, 95 per cent CI 1.1-4.2), but the risk was not increased in the intermediate categories. For endometrioid tumors, risk increased consistently with increasing Quetelet index, and the odds ratio in the highest category was 4.7 (95 per cent CI 1.0-22.7). For both serous and endometrioid tumors, the excess risk was largely confined to premenopausal women. The results of this analysis suggest that for at least some types of ovarian tumor, obesity may warrant further attention as a possible etiologic factor.