Influence of the Body Mass Index and its Effect on Tumor Characteristics and Survival among a Population with Access to Surgical Management of Upper Tract Urothelial Carcinoma.

Objective: To examine the association between the body mass index (BMI) and the risk of survival, and to evaluate whether tumor characteristics differ by BMI in patients with upper tract urothelial carcinoma (UTUC) managed by surgery.

Methods: A clinical series on 876 patients with localized UTUC following nephroureterectomy with a bladder cuff, with data from Osaka Medical College registry (discovery cohort) and the Nagoya group (validation cohort) was examined. In addition to analyzing the overall survival and cancer-specific survival (CSS), the survival impact adjusted by pathological variables was also assessed by the BMI group.

Results: The percentage of high risk features including positive lymphovascular invasion was doubled in the discovery cohort compared to the validation cohort. The group of BMI ≥ 25 kg/m was associated with improved CSS in the discovery cohort (p = 0.004), and this tendency was verified in the validation cohort (p = 0.006). Nonproportional hazards existed for the group of BMI ≥ 25 kg/m and the BMI 18.5-25 kg/m relative to the group of BMI < 18.5 kg/m, with a change in the CSS hazard. In multivariable Cox models, the BMI group had a superior predictive value compared with other pre-clinical factors both in the discovery cohort (HR = 3.85, p = 0.01; 95%CI: 0.09-0.73) and the validation cohort (HR = 1.56, p = 0.01; 95%CI: 0.45-0.91). When adjusted by lymphovascular invasion, the concordance of the model proposed by the discovery cohort (0.52) challenged in the validation cohort was 0.59.

Conclusions: We found a clinically relevant signature for high risk patients with BMI grouping. Further research is necessary on whether tailoring recommendations for weight and nutrition management to tumor characteristics will improve outcomes.