Preliminary treatment results of intensity-modulated radiotherapy for prostate cancer.

Background: To review the initial treatment results of intensity-modulated radiotherapy (IMRT) for prostate cancer.

Methods: Ninety-two patients treated with IMRT before July 2003 were included in this study. The median follow-up was 32 months. The indications for IMRT included primary, adjuvant, and salvage treatment. Combined treatment with androgen suppression therapy was variable. The primary study endpoints were chronic adverse events which were subjectively reported. Only patients with an adenocarcinoma and who had been treated by primary radiotherapy were included in the analysis of disease relapse.

Results: At the time of analysis, 89 patients were still alive, and only 2 patients had died of prostate cancer. In the survival analysis, the 30-month failure-free survival rates were 100%, 89.2%, and 67.3% for the low-, intermediate-, and high-risk groups of patients, respectively. Pretreatment PSA level, Gleason score, risk classification, and adjuvant hormone therapy were significantly associated with relapse according to the univariate analysis, while only risk classification remained significant in the multivariate analysis. During follow-up, 5 (6%) patients developed grade 2 gastrointestinal (GI) adverse events (AE). Sixteen (18%) and 7 (8%) patients developed grade 2 and 3 urinary AE, respectively. Development of severe urinary adverse events was closely related to previous surgical treatment. No factor was identified as being correlated with the GI adverse events. The preservation rate of sexual function was 25.7%.

Conclusions: Seventy-two Grays of irradiation, administered by IMRT, is a safe method as the primary treatment for prostate cancer. However, severe urinary toxicity was related to previous surgical treatment. There is a need for longer follow-up periods to verity the benetit of this dosage level.