Background: Obesity is a bona fide risk factor for ICU admission, mechanical ventilation, and mortality in patients (pts) with COVID-19 in the general population. However, whether obesity is a risk factor in cancer pts remains unknown. Herein, we have conducted a systematic review/meta-analysis of obesity and all-cause mortality in cancer pts with COVID-19. Methods: Following PRISMA guidelines,a systematic search of PubMed and Embase as well as major conference proceedings (ASCO/ESMO/AACR) was conducted for publications from inception to 14 January 2020. Observational studies that reported all-cause mortality in cancer pts with lab confirmation or clinical diagnosis of COVID-19 and BMI (obese (>30 kg/m²) vs. non-obese) were included in the analysis. The pooled odds ratio (OR) and 95% confidence interval (CI) were calculated with the fixed-effects model based on low heterogeneity. Small sample publication bias was evaluated using the Begg’s Funnel Plot and Egger’s test. Results: After reviewing 3387 studies,3 retrospective cohort studies of 419 obese and 1694 non-obese cancer pts (N=2117) with COVID-19 in both inpatient/outpatient settings that reported outcomes based on obesity were found. The 3 studies were conducted multi-nationally in North America, in France, and in the Netherlands respectively. The median ages of the cohorts ranged 66-68. All studies included various cancers of various stages and were of high quality per Newcastle Ottawa scale (scores 7-9). Fixed effects meta-analysis showed no association between obesity and all-cause mortality (OR 0.95, 95% CI 0.74-1.23) in cancer pts with COVID-19. Heterogeneity was low (I² = 33%). No significant funnel plot asymmetry was detected per Egger’s test (P=0.2273). The reported OR of each study is outlined in the table. Conclusions: In contrast to the general population, our analysis reveals that obesity is not associated with increased all-cause mortality in cancer pts with COVID-19. Limitations of this study include a limited number of included studies, reliance on retrospective studies, non-use of ethnicity-specific WHO BMI criteria, and limited granularity of the study-reported BMI. Future prospective studies are warranted to assess the complex interplay among anthropomorphic measures, cachexia/sarcopenia, comorbidities associated with the metabolic syndrome, and COVID-19 outcomes in the cancer pt population.

*Higher OR favors non-obesity (BMI<30 kg/m²), lower OR favors obesity.