Anthropometric Variables, Physical Activity, and Incidence of Ovarian Cancer: The Iowa Women's Health Study

BACKGROUND. Reports on the relation between anthropometric variables (height, weight) and physical activity with ovarian cancer have been inconclusive. The objective of the current study was to extend investigation of potential associations in the Iowa Women's Health Study cohort. METHODS. The relation between self-reported anthropometric variables and incident ovarian cancer was studied in a prospective cohort of women ages 55-69 years who were followed for 15 years. Two hundred twenty-three incident cases of epithelial ovarian cancer were identified by linkage to a cancer registry. RESULTS. No association was found overall between ovarian cancer and height, but a positive association was observed for serous ovarian cancers (relative risk [RR], 1.86 for highest quartile vs. lowest quartile; 95% confidence interval [95% CI], 1.06-3.29). Although current body mass index (BMI) was not associated with ovarian cancer, a BMI ≥ 30 kg/m² at age 18 years appeared to be associated positively with ovarian cancer (multivariate-adjusted RR, 1.83 for BMI ≥ 30 kg/m² vs. BMI < 25 kg/m²; 95% CI, 0.90-3.72), and this association was stronger after exclusion of the first 2 years of follow-up (RR, 2.15; 95% CI, 1.05-4.40). In a multivariate analysis, waist-to-hip ratio was associated with ovarian cancer (RR, 1.59 for highest quartile vs. lowest quartile; 95% CI, 1.05-2.40), but a linear dose response was not found. An index that combined the frequency and intensity of leisure-time physical activity was associated positively with ovarian cancer incidence (multivariate-adjusted RR, 1.42 for high activity vs. low activity; 95% CI, 1.03-1.97). This association was particularly strong for frequency of vigorous physical activity (multivariate-adjusted RR, 2.38 for > 4 times per week vs. rarely/never; 95% CI, 1.29-4.38). CONCLUSIONS. Anthropometric variables were not major risk factors for ovarian cancer in the cohort studied; however, high BMI in early adulthood and frequent and vigorous physical activity may increase the risk of ovarian cancer among postmenopausal women.