Optimal body mass index cut-point for predicting recurrence-free survival in patients with non-muscle-invasive urothelial carcinoma of bladder.

In Japanese patients with non-muscle-invasive urothelial carcinoma of the bladder, the impact of body mass index (BMI) on recurrence following transurethral resection of bladder tumor (TURBT) is unclear. The present study retrospectively examined data collected from 50 patients diagnosed with primary urothelial carcinoma of the bladder (pTa, pTis, and pT1) who had previously undergone TURBT surgery. Two BMI cut-off points for predicting disease recurrence were evaluated: i) A threshold generated through receiver operating characteristic (ROC) curve analysis; ii) the World Health Organization BMI index (24 kg/m2) for overweight status in Japanese populations. Univariate and multivariate analyses were applied to assess individual variables (BMI included) and the effect they had on recurrence-free survival (RFS). Median RFS and BMI values of 19.72 months (range, 3.13-72.13 months) and 23.37 kg/m2 (range, 14.72-36.84 kg/m2), respectively, were recorded. In multivariate analyses, higher continuous BMI was significantly associated with shorter RFS (P=0.019). Based on a ROC-generated BMI cut-off point (23.4 kg/m2), patients were ranked with either a high (≥23.4 kg/m2) or low (<23.4 kg/m2) BMI status. Multivariate analysis indicated that BMI values >23.4 kg/m2 were significantly associated with shorter RFS (P=0.028). Intravesical Bacillus Calmette-Guérin treatment and history of upper-tract urothelial carcinoma were also independently associated (P=0.044 and P=0.010, respectively). However, BMI values >24 kg/m2 (customary cut-off point) had no significant impact on RFS (P=0.066). Thus, a higher BMI status was revealed to be independently predictive of shorter RFS in Japanese patients undergoing TURBT for urothelial carcinoma of the bladder. A greater number of samples are required in order to determine optimal BMI cut-off points in Japanese patients and to investigate whether weight reduction intervention may improve prognosis.