OBJECTIVE: To determine the optimal cystoscopic frequency for intermediate-risk non-muscle invasive bladder cancer. METHODS: Patients with intermediate-risk non-muscle invasive bladder cancer, who underwent transurethral resection of bladder tumor in Peking University People's Hospital from January 2001 to October 2019, were retrospectively analyzed. Their clinical, pathological and follow-up data were collected. In postoperative 2-year period, the patients were underwent cystoscopy every 3 to 6 months. Depending on recurrence and progression of the patients, we hypothesized three strategies of surveillance intensity in the first 2 years after surgery: model 1: 3-month intervals, model 2: 6-month intervals, and model 3: 12-month intervals. The differences in the numbers and time of delayed detection of recurrence and progression were compared among the three models. RESULTS: A total of 185 patients were enrolled, including 144 males (77.8%) and 41 females (22.2%). The median age was 68 (59-76) years. There were 118 cases (63.8%) with single tumor and 67 cases (36.2%) with multiple tumor. Of the patients 179 (96.8%) had stage Ta and 6 (3.2%) had stage T1. There were 108 cases (58.4%) with high-grade disease and 77 cases (41.6%) with low-grade disease. During the follow-up period of the first 2 years, 52 patients (28.1%) had recurrence, 133 cases (71.9%) had no recurrence, 11 cases (5.9%) had progression and 174 cases (94.1%) had no progression. Compared with model 1, 29 (55.8%) delayed detection of recurrence in model 2 vs. 41 (78.8%) delayed detection of recurrence in model 3, and the difference was statistically significant (P=0.012). The median delayed time of detecting recurrence was 1.00 months in model 1, 1.99 months in model 2 and 4.19 months in model 3, respectively. There were statistically significant differences between mode 1 and model 3 (P=0.001), and between model 2 and model 3 (P=0.013). Compared with model 1, 5 (45.4%) delayed detection of progression in model 2 vs. 8 (72.7%) delayed detection of progression in model 3, and the difference was not statistically significant. The median delayed time of detecting progression was 1.00 month in model 1, 2.00 months in model 2 and 3.00 months in model 3, respectively. There was no statistically significant difference among them. CONCLUSION: Although providing slightly slower detection of tumor recurrence and progression, compared with 3-month intervals of cystoscopy, 6-month intervals do not result in serious adverse outcomes and reduce cost and pain of the patients, which is feasible in intermediate-risk non-muscle invasive bladder cancer.
