Jennifer A. Ritonja

Sleep duration and the risk of epithelial ovarian cancer

Variations in sleep duration have been linked to biological mechanisms that may affect cancer risk. We investigated the association between sleep duration during adult life and the risk of epithelial ovarian cancer overall, and according to tumor behavior and invasive cancer type, in a population-based case-control study. Among 465 cases and 855 controls, sleep duration during life periods starting at age 20 years was assessed, with which average sleep during adult life was calculated. Unconditional multivariable logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI). Polytomous logistic regression was used to estimate associations by tumor behavior (invasive vs. borderline) and invasive cancer type (Type I vs. II). Compared to an average sleep duration during adult life of the recommended 7-9 h/night, the ORs (95% CI) for ovarian cancer overall were 1.04 (0.74-1.46) and 1.78 (1.15-2.75) for  9 h/night, respectively. An increased risk with > 9 h/night was also observed for invasive and borderline tumors and among Type I and Type II invasive cancer types. The results suggest that sleep durations longer than the recommended 7-9 h/night during adulthood may be associated with an increased ovarian cancer risk.

Trajectories of body fatness in adulthood and the risk of ovarian cancer.

While excess body fatness in older adulthood has been linked to ovarian cancer, the influence of changes in body fatness over time is unclear. This study examined the association between adulthood trajectories of body mass index (BMI), a proxy for body fatness, and ovarian cancer. In a population-based case-control study (440 cases, 820 controls), we used a group-based trajectory approach to identify BMI trajectories from age 20-70. Using unconditional logistic regression, we estimated adjusted odds ratios (aOR) and 95 % confidence intervals (95 % CI) for the associations between the estimated trajectories and ovarian cancer. We identified three distinct BMI trajectories: a normal-stable trajectory, a normal-to-overweight trajectory and an overweight-to-obese trajectory, which included 63.2 %, 31.0 % and 6.8 % of the population, respectively. Multivariable aORs suggested that participants with normal weight at the onset of adulthood who became overweight over their adulthood time did not differ in their risk of ovarian cancer compared to those who maintained a normal weight throughout adulthood (aOR (95 %CI): 0.89 (0.69-1.16)). Among those in the overweight-to-obese trajectory, the aOR (95 %CI) was 1.45 (0.87-2.43), and thus in the direction of an increased ovarian cancer risk compared to those who maintained a normal weight. Our findings underscore the need for further research to clarify the role of body fatness across the lifetime in the etiology of ovarian cancer.