Physical activity, body size and composition, and risk of ovarian cancer

Objectives We examined the association between risk of ovarian cancer and physical activity and anthropometry (body mass index, height, waist, fat, and fat-free mass) in the Melbourne Collaborative Cohort Study. Methods This prospective cohort study included 18,700 women aged 26-76 years old at recruitment between 1990 and 1994. Participants were interviewed about their physical activity, including frequency and intensity. Body measurements were taken directly; fat mass and fat-free mass were calculated from bioelectrical impedance analysis. During an average of 10.2 years of follow-up, 113 ovarian cancers were ascertained. Cox regression was used to estimate hazard ratios. Results After adjusting for potential confounders, compared with no physical activity, the hazard ratios for levels of total physical activity were 1.56 (95% CI: 0.81, 3.00) for low level, 1.92 (1.07, 3.45) for medium level, and 2.21 (1.16, 4.24) for high level (test for trend, p = 0.01). The hazard ratio for ovarian cancer in relation to BMI was 1.22 (95% CI: 1.00, 1.48; p-trend, 0.06) per 5 kg/m² increment, and for fat mass, 1.23 (95% CI: 1.01, 1.49; p-trend, 0.04) per 10 kg increment. Conclusions This study found some evidence for a possible relationship between higher levels of physical activity and body size and increased ovarian cancer risk.