High dose rate brachytherapy of localized prostate cancer

OBJECTIVE: We evaluated the safety and efficacy of high dose rate (HDR) brachytherapy using Iridium-192 (Ir 192) and 3D conformal external beam radiotherapy in patients with localized prostate cancer. METHODS: A total of 444 patients with localized prostate cancer underwent combined radiotherapy with interstitial Ir 192 and 3D conformal external beam radiotherapy between December 1992 and March 2001. The 230 patients, treated between December 1992 and December 1997 were analyzed. All patients underwent laparoscopic pelvic lymph node dissection to exclude patients with lymphatic involvement. Ir 192 was delivered twice with a 1-week interval in HDR remote control technique. The interstitial dose from December 1992 to December 1993 was 10Gy, after December 1993 the dose was reduced to 9Gy per treatment session. The interstitial application was followed by external beam radiation of 45Gy for cT1-cT2 and 50.4Gy for cT3 tumor (40Gy from December 1992 to December 1993). Progression was defined as biochemical failure according to ASTRO criteria, e.g. three consecutive PSA rises following the PSA nadir. RESULTS: The median PSA value decreased from 12.8 to 0.93ng/ml 12 months after treatment. Median PSA value was 0.47 after 24 months, 0.30ng/ml after 36 months and 0.18ng/ml after 60 months. 68% of the biopsies were negative 24 months after therapy. Progression-free rate was 100% for cT1 tumors, 75% for cT2 and 60% for stage-cT3 on 5-year follow-up. Five-year overall survival was 93%, 5-year disease-specific survival was 98%. Initial PSA value <10ng/ml, low stage and low grade were significantly related to 5-year progression-free survival. CONCLUSIONS: Combined HDR brachytherapy with Ir 192 is an alternative treatment option especially for patients with cT3 prostate cancer. Initial PSA value, stage and grade, are important prognostic factors.