SIU 2017: The Prognostic Implication of Body Mass Index on Postoperative Survival Outcomes in Non-Metastatic Renal Cell Carcinoma

Lisbon, Portugal ( Obesity is well-known risk factor for the development of renal cell carcinoma (RCC). However, the impact of obesity on patients' survival outcomes after nephrectomy has not been clearly established thus far. The authors aimed to evaluate the association between body mass index (BMI) and Survival outcomes in patients with non-metastatic RCC, including overall survival (OS), cancer specific survival (CSS), and recurrence free survival (RFS).

A single-institutional retrospective analysis was implemented on 2329 patients who underwent radical or partial nephrectomy for non-metastatic RCC from 2000 to 2014. Enrolled patients were grouped into normal (BMI <23kg/m2, n=705), overweight (BMI 23–24.9 kg/m2, n=648), and obese (BMI >25kg/m2, n=976) according to BMI cut-offs for Asian population. 

Several clinico-pathological factors, including asymptomatic presentation, being female, lower transfusion rate, higher proportion of clear cell histology, and lower frequency of nodal invasion, were observed to be associated with the obese group (all p<0.05). Obese group showed significantly better 5-year RFS (90.7% vs 84.9%, p<0.001), OS (91.8% vs 86.8%, p=0.002), and CSS (94.8% vs 89.4%, p=0.002) rates than normal patients. On multivariable analysis, BMI as continuous variable independently correlated with favorable RFS (hazard ratio HR 0.93; 95% confidence interval (CI) 0.89-0.97, p=0.002), OS (HR 0.95; 95% CI 091-0.99, p=0.033) and CSS (HR 091; 95% CI 0.86-0.97, p=0.002). In addition, multivariable analysis revealed overweight (HR 0,57, 95% CI 0370.87, p=0.009) and obese patients (HR 0.58; 95% CI 0.39-0.87, p=0.009) were associated with significantly reduced risk of RCC related death compared to normal patients.

This data suggest that overweight and obesity, defined as increasing BMI, are generally related to favorable survival outcomes after nephrectomy for non-metastatic RCC. Further research will be required to discover the biological mechanisms behind this positive correlation between.

Presented by: Hyung Suk Kim
Affiliation: Dongguk University Ilsan Medical Center, Goyang, South Korea

Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre.Twitter: @GoldbergHanan at the 37th Congress of Société Internationale d’Urologie - October 19-22, 2017- Lisbon, Portugal