Prediction of recurrence risk in patients with non-muscle-invasive bladder cancer

Objective: Non-muscle-invasive bladder cancer (NMIBC) remains a common challenge in uro-oncology with conflicting reports on recurrence risk. This study aimed to elucidate the recurrence rate of NMIBC in the Cancer Clinic of Shahid Beheshti Hospital in Iran and to investigate related parameters affecting recurrence risk. Methods: The data of 143 patients with NMIBC, who underwent treatment between January 2017 and January 2020 and were followed up from the initial transurethral resection of bladder tumor until November 30, 2020 in our institution, were retrospectively assessed. The Cox regression analysis and Kaplan-Meier plot of recurrence-free survival were used to determine independent contributing factors for tumor recurrence. Results: Among patients with NMIBC, 83.9% were male, and 16.1% were female, with a mean age of 64.4 (standard deviation [SD] 12.9) years. During the follow-up, 71 (49.7%) patients showed tumor recurrence, with a mean recurrence time of 11.5 (SD 6.9) months. In the Chi-square test or Fisher's exact test, the age (>= 65 years) (p=0.037), obesity (body mass index >= 30 kg/m(2)) (p=0.004), no diabetes mellitus (p=0.005), smoking (current or former smoker) (p=0.001), immediate perfusion therapy (p=0.035), number of tumors (>3) (p<0.001), and tumor stage (Ta, T1, and Tis) (p=0.001) had independent significant effects on the recurrence of NMIBC. The multivariate Cox regression analysis indicated that preoperative obesity (hazards ratio [HR] 7.90; 95% confidential interval [CI] 4.01-15.55; p<0.001), current or former smoking (HR 1.85; 95% CI 1.07-3.20; p=0.027), and a high-grade tumor (HR 4.03; 95% CI 1.59-10.25; p=0.003) were significant predictors of tumor recurrence. The Kaplan-Meier plot of recurrence-free survival showed that obesity (log-rank p<0.001), current or former smoking (log-rank p=0.001), and a high-grade tumor (log-rank p=0.006) were associated with a shorter time interval until the first tumor recurrence. Conclusion: The study found a high recurrence rate of NMIBC in Iran from January 2017 to January 2020, with the obesity, smoking history, and the high-grade tumor as contributing factors.