Impact of Body Mass Index on Survival Outcomes of Patients with Metastatic Renal Cell Carcinoma in the Immuno-oncology Era: A Systematic Review and Meta-analysis

Abstract

Context: Body mass index (BMI) is a useful tool for measuring body composition. It is unclear whether high BMI is a favourable indicator in patients with metastatic renal cell carcinoma (mRCC) treated with immune checkpoint inhibitors (ICIs).

Objective: To investigate the prognostic significance of BMI in patients with mRCC treated with ICIs in a systematic review and meta-analysis.

Evidence acquisition: Ovid MEDLINE, Embase, and Web of Science were systematically searched in July 2021, and meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

Evidence synthesis: A total of 517 nonduplicate citations were screened by title and abstract, followed by full-text screening of 57 candidate articles to determine whether each study met the eligibility criteria. Overall, a total of 2281 patients from eight studies were included in the systematic review and meta-analysis. BMI levels were compared with overall survival (OS) and progression-free survival (PFS) in seven and three studies, respectively. Overweight/obese BMI was significantly associated with better OS compared to normal BMI (adjusted hazard ratio [aHR] 0.77, 95% confidence intervals [CI] 0.65-0.91; p = 0.002). A similar trend was observed for PFS (aHR 0.66, 95% CI 0.44-1.00; p = 0.050). There was no statistical heterogeneity or obvious publication bias among these studies.

Conclusions: This is the first systematic review and meta-analysis to evaluate the impact of BMI on survival outcomes of patients with mRCC treated with ICIs. To confirm the existence of the obesity paradox for patients with mRCC in the immuno-oncology era, high-quality clinical trials and basic research are warranted.

Patient summary: We reviewed published data on survival outcomes of 2281 patients with metastatic kidney cancer treated with immunotherapy drugs in relation to their body mass index (BMI). We found that higher BMI was associated with better survival when compared to normal BMI for this disease setting and treatment strategy.

Keywords: Body mass index; Immune checkpoint inhibitors; Meta-analysis; Obesity; Prognosis; Renal cell carcinoma.

Fig. 1

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) diagram depicting the flow of information through the literature search and article selection. BMI = body mass index; HR = hazard ratio.

Fig. 2

(A) Forest plot of the meta-analysis of the crude HR for OS according to overweight/obese versus normal BMI. (B) Forest plot of the meta-analysis of the adjusted HR for OS according to overweight/obese versus normal BMI controlled for other prognostic factors. (C) Funnel plot of the meta-analysis of the adjusted HR for OS with the effect estimates against their SEs on a reversed scale. BMI = body mass index; CI = confidence intervals; df = degrees of freedom; HR = hazard ratio; IV = inverse variance; OS = overall survival; SE = standard error.

Fig. 3

(A) Forest plot of the meta-analysis of the crude HR for PFS according to overweight versus normal BMI. (B) Forest plot of the meta-analysis of the adjusted HR for PFS according to overweight versus normal BMI controlled for other prognostic factors. (C) Funnel plot of the meta-analysis of the adjusted HR for PFS with the effect estimates against their SEs on a reversed scale. BMI = body mass index; CI = confidence intervals; df = degrees of freedom; HR = hazard ratio; IV = inverse variance; PFS = progression-free survival; SE = standard error.