Prognostic significance of bladder neck involvement in non‐muscle‐invasive bladder cancer: A SEER database analysis with 19,919 patients

PURPOSE: To study prognostic values of bladder neck involvement (BNI) and survival outcomes in non‐muscle‐invasive bladder cancer (NMIBC). METHOD AND MATERIALS: The national Surveillance, Epidemiology, and End Results database (2004–2015) was applied to gain further insight into the prognostic values of BNI and 19,919 patients diagnosed with NMIBC were included in our study. We used the Kaplan–Meier method with the log‐rank test and subgroup analyses to evaluate cancer‐specific survival (CSS) and overall survival (OS). In addition, the multivariable Cox proportional hazard model and propensity score matching (PSM) were utilized. RESULTS: In all, 3446 patients with BNI and 16,473 patients with sites except for bladder neck were enrolled in our study. Compared with other sites, a tendency toward a higher proportion of higher grade (p < 0.001), bigger tumor size (p < 0.001), and more patients with T1 and Tis stage (p < 0.001) was seen in BNI group. After 1:1 PSM, 3425 matched pairs were selected. Under the survival analyses, the BNI group had a lower survival probability in both OS (p = 0.0056) and CSS analyses (p < 0.0001) in NMIBC patients. However, in the subgroup analysis, only observed in the Ta and T1 stage in terms of CSS (all p < 0.05), and patients with Tis stage failed to show statistical survival differences (p > 0.05). In addition, subgroups stratified by tumor size and grade all revealed poor prognosis of BNI in NMIBC patients. Moreover, better survival outcomes of OS were observed in BNI patients who received radical cystectomy (p = 0.02) or chemotherapy (p < 0.001) multivariable Cox regression after PSM revealed that the BNI group had a higher risk of overall mortality (OM) (BNI vs. other sites hazards ratios [HR]: 1.127, 95% CI: 1.154–1.437, p < 0.001) and cancer‐specific mortality (CSM) (BNI vs. other sites HR: 1.127, 95% CI: 1.039–1.223, p < 0.001), while before PSM, similar situations were only existed in CSM (BNI vs. other sites HR: 1.288, 95% CI: 1.154–1.437, p < 0.001). CONCLUSIONS: The prognosis of BNI was poorer than that of the other sites. BNI was an independent risk factor for OM and CSM in patients with NMIBC, especially for those with Ta or T1 stage.