Obesity paradox: is a high body mass index positively influencing survival outcomes in gynecological cancers? A systematic review and meta-analysis

Objective Obesity represents an exponentially growing preventable disease leading to different health complications, particularly when associated with cancer. In recent years, however, an 'obesity paradox' has been hypothesized where obese individuals affected by cancer counterintuitively show better survival rates. The aim of this systematic review and meta-analysis is to assess whether the prognosis in gynecological malignancies is positively influenced by obesity. Methods This study adheres to PRISMA guidelines and is registered with PROSPERO. Studies reporting the impact of a body mass index (BMI) of >30 kg/m(2) compared with <30 kg/m(2) in patients with gynecological cancers listed in PubMed, Google Scholar and ClinicalTrials.gov were included in the analysis. The Quality Assessment of Diagnostic Accuracy Studies 2 tool (QUADAS-2) was used for quality assessment of the selected articles. Results Twenty-one studies were identified for the meta-analysis, including 14 108 patients with cervical, ovarian, or endometrial cancer. There was no benefit in 5-year overall survival for obese patients compared with non-obese patients (OR 1.2, 95% CI 1.00 to 1.44, p=0.05; I-2=71%). When pooling for cancer sub-groups, there were no statistically significant differences in 5-year overall survival in patients with cervical cancer and 5-year overall survival and progression-free survival in patients with ovarian cancer. For obese women diagnosed with endometrial cancer, a significant decrease of 44% in 5-year overall survival (p=0.01) was found, with no significant difference in 5-year disease-free survival (p=0.78). Conclusion According to the results of the present meta-analysis, a BMI of >= 30 kg/m(2) does not have a positive prognostic effect on survival compared with a BMI of <30 kg/m(2) in women diagnosed with gynecological cancers. The existence of the 'obesity paradox' in other fields, however, suggests the importance of further investigations with prospective studies.