163. Radical radiotherapy for muscle-invasive bladder cancer: The influence of total radiation dose and overall treatment time on disease outcome

Abstract

Purpose To assess the influence of total radiation dose, overall tratment time and other clinical factors on treatment outcome for muscle-invasive (T2,T3) bladder cancer patients, treated with radical radiotherapy. Material and methods Between 1975 and 1995, 480 consecutive patients with T2, T3 bladder cancer were treated with radical radiotherapy. During that period various fractionation schedules were used: 1. conventional fractionation (once a-day, 1.8–2.5 Gy/fraction; OTT-53 days), 2. protracted fractionation (once a-day, pelvis- 1.6–1.7 Gy/fraction, boost- 2.0 Gy/fraction; OTT-62 days), 3. accelerated hyperfractionated boost (pelvis- once a-day, 2.0 Gy/fraction; boost- twice a-day, 1.3–1.4 Gy/fraction; OTT-45 days), 4. accelerated hyperfractionation (pelvis and boost- twice a-day, 1.2–1.5 Gy/fraction; OTT-41 days). For the whole group of patients mean total dose and mean overall treatment time were: 65.5 Gy and 51 days, respectively. Maximum-likelihood logistic model and Cox proportional hazard model were used to evaluate the role of total dose, overall treatment time, T-stage, hemoglobin level and bladder capacity before radiotherapy. The median follow-up was 76 months. Results Five-years actuarial local control rate was 47% and overall survival rate was 40%. Logistic model including total dose, overall treatment time and T-stage revealed that all those factors significantly influenced local control probability (p=0.021 for TD, p=0.038 for OTT and p=0.00068 for T-stage). When other clinical factors and tratment-related parameters were analysed in Cox proportional hazard model the results were as follows: Hb-level and bladder capacity before radiotherapy significantly influenced local control and overall survival, total radiation dose was of borderline significance for overall survival (p=0.065) but overall treatment time was not significant parameter. Conclusions Our study suggest that, higher total radiation dose may be related to better treatment outcome. The effect of overall treatment time is difficult to define, because its role depends on influence of other prognostic factors. The most important factors for treatment outcome are: hemoglobin level, bladder capacity before radiotherapy and T-stage.