High Ki-67 Expression Predicts Favorable Survival in Muscle-Invasive Bladder Cancer Patients Treated With Chemoradiation-Based Bladder-Sparing Protocol

Purpose To evaluate associations of Ki-67 expression with oncologic outcomes in muscle-invasive bladder cancer (MIBC) patients treated with chemoradiotherapy (CRT)-based bladder-sparing protocol. Materials and Methods Between 1998 and 2011, 190 consecutive MIBC patients were treated with CRT-based bladder-sparing protocol. After transurethral resection of the bladder tumor, the patients underwent induction CRT (40 Gy with concurrent cisplatin) followed by partial cystectomy for bladder preservation or radical cystectomy (RC). Included in this study were 94 patients who were histologically diagnosed with urothelial carcinoma and whose tumor tissues before CRT were available for immunohistochemical evaluation of Ki-67 expression status. Results After induction CRT, 16 (17%) and 53 (56%) patients underwent partial cystectomy and RC, respectively, while the remaining 25 (27%) did not undergo cystectomy. Successful bladder preservation was achieved in 34 patients (36%). Higher Ki-67 labeling index (LI) independently predicted CRT response clinically and pathologically. Among the clinicopathologic variables available before CRT and cystectomy, high Ki-67 LI (≥ 20%) was independently associated with better cancer-specific survival (CSS) (5-year CSS rate, 78% vs. 46% for low Ki-67 LI; P = .019). The difference in CSS according to Ki-67 expression status was more remarkable in patients with cT3 disease (5-year CSS rate, 72% vs. 29%; P = .0098). Conclusion High Ki-67 expression predicts favorable CSS in MIBC patients treated with CRT-based bladder-sparing protocol. MIBC patients with high Ki-67 expression status might benefit from CRT-based multimodal approaches in terms of prognosis and quality of life as a result of bladder preservation.