Increased body mass index (BMI) may increase the risk of disease recurrence and progression among patients with T1G3 non-muscle-invasive bladder cancer (NMIBC), according to a study published in World Journal of Urology.1

The association between obesity and poorer outcomes for various cancers, including breast, prostate, and ovarian cancers, have been well established. Evidence for the affect of obesity on outcomes for bladder cancer, however, have been conflicting and require further study.

Researchers assessed the outcomes of 1155 patients with T1G3 NMIBC who underwent transurethral resection of the bladder tumor (TURBT); re-TURBT was performed within 6 weeks after the first procedure. Eligible patients received adjuvant intravesical BCG immunotherapy with maintenance. Multivariable Cox regression analyses were performed to identify factors predictive of recurrence and progression, and follow-up was conducted every 3 months.

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Overall, 288 (27.53%) and 867 (82.89%) patients had residual high-grade NMIBC or were negative after re-TURBT, respectively. During the follow-up period, 64.82% of patients had disease recurrence, 30% had progression; 14.34% of patients died from all-causes and 7.36% died of bladder cancer.

Multivariable analyses showed that being overweight (hazard ratio [HR], 4.0; P < .001) or obese (HR, 5.33; P < .001) significantly increased the risk of recurrence. Adding BMI to a model including standard clinicopathological factors increased the C-index (a standard performance measure for survival analysis models) by 9.9.

Being overweight (HR, 2.52; P < .001) or obese (HR, 2.521; P < .001) also significantly increased the risk of progression. The addition of BMI increased the C-index by 1.9.

Other predictive factors for an increase in risk of recurrence were tumor size (hazard ratio [HR], 1.3; P = .001) and multifocality (HR, 1.24; P = .004). Risk factors significantly associated with an increased risk for progression were tumor size (HR, 1.63; P < .001), multifocality (HR, 1.31; P = .01), and concomitant carcinoma in situ (HR, 2.07; P < .001).

The authors concluded that “taking into account this anthropometric factor at the initial diagnosis and when planning the therapeutic strategy could be relevant in the clinical management of T1G3 NMIBC. Future studies are needed to better define the impact of the BMI in clinical decision making for these patients.”


  1. Ferro M, Vartolomei MD, Russo GI, et al. An increased body mass index is associated with a worse prognosis in patients administered BCG immunotherapy for T1 bladder cancer [published online July 10, 2018]. World J Urol. doi: 10.1007/s00345-018-2397-1