Purpose: To investigate whether the addition of chemotherapy to radiotherapy (RT) is beneficial particularly in bladder tumors that possess the capacity for rapid proliferation.
Patients and methods: The Ki-67 index was evaluated by immunohistochemistry on pretreatment biopsies from 136 patients treated by transurethral tumor resection (TURBT) and RT (n=50) or platin-based radiochemotherapy (RCT; n=86). Ki-67 expression was correlated with response to RT/RCT and long-term local control rates. The median follow-up was 43 months.
Results: The percentage of Ki-67-positive cells ranged from 1.5% to 89%. Complete response (CR) was observed in 100/131 patients (76%, five without restaging TURBT). A statistically significant association between high Ki-67 index (>or= median) and CR was noted for patients receiving RCT (93% vs. 66% for Ki-67 < median; p=0.001), but not for patients treated with RT alone (p=0.12). Long-term local control was 39% for patients treated with RT, and 44% for patients after RCT (p=0.49). Patients with high Ki-67 index did significantly better when subjected to combined RCT (55% vs. 33% with low Ki-67 index; p=0.006), whereas no difference between high and low Ki-67 status was observed in the RT group (39% each; p=0.57). On multivariate analysis, Ki-67 status was an independent predictor for local failure in the RCT group (risk ratio, 0.43; p=0.007). Disease-specific survival was significantly better after RCT (62%) as compared with RT (42%; p=0.03), however, the Ki-67 index was not related to this endpoint.
Conclusion: Rapid proliferation is associated with improved local control, if patients are treated with concurrent RCT. The cytostatic effect of concurrent chemotherapy may effectively inhibit repopulation during fractionated RT.