Aim: The aim of this study was to examine the association between obesity, as measured by body mass index (BMI), and overall survival in a cohort of Australian women with ovarian cancer. We also conducted a systematic review of all available evidence to quantify the magnitude of the association between obesity and ovarian cancer survival using meta-analysis.
Methods: This analysis included 1,399 women with histologically confirmed invasive epithelial ovarian cancer diagnosed between 2002 and 2006. Information about pre-diagnostic BMI and other lifestyle factors was obtained via a self-administered questionnaire. Clinicopathologic data were abstracted from the women’s medical records and deaths in the cohort were ascertained from medical records and/or the Australian National Death Index. Crude 5-year survival probabilities were estimated using the Kaplan-Meier technique, and adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were obtained using Cox regression models. For the systematic review, relevant studies were identified using Medline and Embase databases up to April 2012. Random-effects models were used to calculate pooled hazard ratios.
Results: The cohort was followed for survival until October 2011. The 5-year survival was 48%. The strongest clinicopathologic predictors of survival were FIGO stage, histological grade, residual disease and age at diagnosis. After adjustment, a survival disadvantage was observed for women who were obese prior to diagnosis compared to women in the normal BMI range (BMI 30-34.9: HR 1.21, 95% CI 0.99-1.48; BMI≥35: HR 1.19, 95% CI 0.91-1.54). In the meta-analysis of fifteen studies the overall pooled estimate for obese versus non-obese women was pHR 1.18 (1.05-1.31).
Conclusions: The results of these analyses suggest that women with ovarian cancer who are obese have worse survival compared to those who are not obese. The mechanism underlying this association is not yet known and is an important area for future research.