The retrospective analysis of an ovarian cancer collective by Pavelka et al.1 showed a higher percentage of stage I disease (according to the International Federation of Gynecology and Obstetrics staging system) in obese patients and a trend toward an unfavorable survival in patients with advanced-stage disease. This led the authors to suggest that obesity has a negative effect on tumor biology and is an adverse prognostic factor in ovarian cancer. Our own data speak against this hypothesis.
First, Pavelka et al. used the documented higher incidence of ovarian cancer in obese patients as a natural argument for a more aggressive tumor behavior in case of disease. They should be aware that factors of influence may play different roles in both situations. Examples are the BRCA1/BRCA2 mutations, which promote ovarian cancer incidence but are associated with a more favorable outcome, and parity, which reduces ovarian cancer incidence but has an adverse effect on survival.
Second, the authors used only 216 datasets for their statements after various exclusion processes. They did not state the initial number of patients or the number of patients excluded for various reasons, making it impossible to estimate the magnitude of the potential bias. Therefore, we repeated the analyses in our collective of >1000 patients with ovarian carcinoma, including 695 datasets with complete information on body mass index, tumor stage and grade, tumor-associated death, and long-term survival. Among these were 121 patients who had an additional immunohistochemical profile of the primary tumor. Analyses of this collective regarding other aspects have been published.
In summary, we observed no influence of obesity on tumor stage, tumor grade, tumor proliferation (Ki-67 antigen), or on the expression of the steroid hormone receptors, estrogen and progesterone. Thus, factors that clearly are linked with aggressive tumor biology or targets of obesity-associated, endogenous steroid hormone action failed to show any positive correlation. On the contrary, tumors in obese patients showed a slight and not significant trend toward better tumor differentiation and lower proliferation. Kaplan-Meier survival analyses revealed no influence of obesity, even when patients with or without postoperative residual tumor were considered.
We are aware of the risks of obesity, its relation to cancer incidence, and the fact that obesity generally should be avoided. However, there is no serious evidence that obesity has a significant influence on the biology and prognosis of ovarian cancer.