Effect of body mass index on the outcomes of patients with upper and lower urinary tract cancers treated by radical surgery: results from a Canadian multicenter collaboration

Objective: To evaluate the effect of body mass index (BMI) on the outcomes of patients with urinary tract carcinoma treated with radical surgery.

Materials and methods: Data were collected from 10 Canadian centers on patients who underwent radical cystectomy (RC) (1998-2008) or radical nephroureterectomy (RNU) (1990-2010). Various parameters among subsets of patients (BMI < 25, 25 ≤ BMI < 30, and BMI ≥ 30 kg/m(2)) were analyzed. Kaplan-Meier and multivariate analyses were performed to assess the effect of BMI on overall survival, disease-specific survival, and recurrence-free survival (RFS).

Results: Among the 847 RC and 664 RNU patients, there was no difference in histology, stage, grade, and margin status among the 3 patient subsets undergoing either surgery. However, RC patients with lower BMIs (< 25 kg/m(2)) were significantly older (P = 0.004), had more nodal metastasis (P = 0.03), and trended toward higher stage (P = 0.052). RNU patients with lower BMIs (< 25 kg/m(2)) were significantly older (P = 0.0004) and fewer received adjuvant chemotherapy (P = 0.04) compared with those with BMI ≥ 30 kg/m(2); however, there was no difference in tumor location (P = 0.20), stage (P = 0.48), and management of distal ureter among the groups (P = 0.30). On multivariate analysis, BMI was not prognostic for overall survival, disease-specific survival, and RFS in the RC group. However, BMI ≥ 30 kg/m(2) was associated with more bladder cancer recurrences and worse RFS in the RNU group (HR = 1.588; 95% CI: 1.148-2.196; P = 0.0052).

Conclusions: Increased BMI did not influence survival among RC patients. BMI ≥ 30 kg/m(2) is associated with worse bladder cancer recurrences among RNU patients; whether this is related to difficulty in obtaining adequate bladder cuff in patients with obesity requires further evaluation.