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There is by now accumulating evidence that high radiation dose (> 75 Gy) is necessary for tumour control when treating intermediate and high risk prostate cancer. To treat safely at high doses with external beam therapy, 3-Dimensional Conformal Radiotherapy (3d-CRT) or Intensity Modulated Radiotherapy (IMRT) techniques must be used. In this way, using the IMRT as standard of care with the use of validated position verification protocol the toxicity can be limited while the dose to the prostate is escalated. However, despite the use of IMRT, the incidence rates for GI and GU toxicity are still high. Other means to give high does on the prostate is the combination of IMRT and high dose rate (HDR) or pulse dose rate (PDR).brachytherapy. The main advantage of brachytherapy is the limited dose in neighbouring organs and potentially less toxicity. Many publications have shown a lower toxicity profile for the combination treatment.
In this study difference in outcome of treatment between IMRT only and IMRT+BRACHY will be investigated in a prospective randomized setting. It is hypothesized that the incidence of grade > 2RTOG long term genitourinary (GU) and gastrointestinal (GI) toxicity of IMRT+BRACHY is half that of IMRT only (3 year incidence is 15% vs 30%). Less long-term toxicity is expected with IMRT+BRACHY differences. Because long term toxicity has a major affect on the quality of life ot the patient, this needs to be assessed with validated questionnaires. Because the dose to the prostate is similar for both groups, no difference in tumour control, expressed as Biochemical DIsease Free Survival (bDFS) and relapse free survival (RFS) is anticipated.
In the phase III prospective multi center trial prostate cancer patients belonging to the intermediate- and partially high risk profile, will be randomized to: Arm 1, treated with radiotherapy IMRT only or Arm 2: treated with combination IMRT+BRACHYtherapy. Both techniques of brachytherapy, HDR or PDR are allowed. The target number of patients will be 240 patients. Expected duration of accrual will be 3 years in 8 Netherlands hospitals.
The primary study objective is to show a 50% reduction of the incidence of long-term gastrointestinal and genitourinary toxicity in the treatment of prostate cancer in the intermediate and high risk group by treatment with IMRT followd by brachytherapy (IMRT+BRACHY) compared to treatment with IMRT alone. Secondary objectives are to investigate the effect of the combined treatment on acute toxicity, tumour control, Quality of Life, overall survival, costs and cost-effectiveness compared to standard treatment with IMRT alone.
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