Influence of preoperative body mass index on prognosis for patients with upper urinary tract urothelial carcinoma treated with radical nephroureterectomy

Abstract

Purpose: The impact of body mass index (BMI) on patients with upper urinary tract urothelial carcinoma (UTUC) undergoing radical nephroureterectomy (RNU) is controversial. Increasing evidence suggests an age-dependent relationship between obesity and outcomes for some solid organ tumors. Herein, we aimed to assess the prognostic value of preoperative BMI in UTUC patients treated with RNU in Taiwan.

Methods: This was a retrospective single-center study of 468 UTUC patients undergoing RNU during January 2010-December 2017, with preoperative BMI classification and subgroup analysis based on ages of < or ≥ 70 years. All UTUC patients underwent RNU and bladder cuff excision. Overall survival (OS), cancer-specific survival, and disease-free survival (DFS) were analyzed. Fisher's exact test, Mann-Whitney U test, Kaplan-Meier method, and Cox regression model were used for data analysis.

Results: The median follow-up duration was 36 months. Patients with higher versus lower BMI (cutoff: 25 kg/m²) showed no differences in OS; older patients had poor OS (hazard ratio [HR] 1.74; 95% confidence interval [CI] 1.24-2.40; p < 0.001). Older age was an independent predictor of poor OS in multivariate Cox regression analysis (p = 0.001). Younger patients with higher BMI (p = 0.02) had better DFS than older patients with no BMI-related survival differences. Higher BMI was an independent predictor of favorable DFS in younger patients in multivariate Cox regression analysis (HR, 0.53; 95% CI 0.28-0.99; p = 0.043).

Conclusion: Younger UTUC patients with higher BMI were independently associated with a favorable DFS.

Keywords: Body mass index; Nephroureterectomy; Obesity paradox; Upper urinary tract urothelial carcinoma.