Does body mass index affect survival of patients undergoing radical or partial cystectomy for bladder cancer?

Obesity is estimated to account for up to 20% of all cancer deaths. We evaluated the effect of body mass index (BMI) on survival in patients undergoing radical or partial cystectomy for bladder cancer.

Pathological and medical records on 300 consecutive patients undergoing radical or partial cystectomy for invasive bladder cancer between January 1990 and December 1993 were reviewed. The standard WHO definition of BMI was used, that is normal weight-less than 25 kg/m, overweight-25 to 29.9 kg/m and obesity-30 kg/m or greater. Sufficient data were available on 288 of 300 patients (96%) with cystectomy (radical in 264 and partial in 24) for analysis.

The BMI distribution was normal weight in 34% of patients, overweight in 41% and obesity in 25%. Mean followup was 53.4 months (median 39, range 1 to 168). Median overall survival was 43.0 months (95% CI 37.1 to 58.4), while median disease specific survival was 82.5 months (95% CI 50.0 to 127.5). Multivariate analysis revealed that age greater than 65 years, pathological stage, smoking history and soft tissue margin status as significant factors impacting overall survival (p <0.05). Pathological stage was organ confined (less than pT3a) in 51% of cases. BMI was not associated with disease specific survival as a continuous (p = 0.17) or categorical (p = 0.51) variable. Although it was insignificant, unadjusted analysis showed lower disease specific mortality in patients with a BMI of less than 25 mg/kg and organ confined disease (p = 0.08).

There was no significant association between BMI and overall or disease specific survival, although there may be a trend toward better disease specific survival in normal weight (BMI less than 25 kg/m) patients with organ confined disease (p = 0.08).