High dose rate (HDR) brachytherapy with conformal radiation therapy for localized prostate cancer.

OBJECTIVES

To evaluate the outcome of high dose rate (HDR) brachytherapy with iridium 192 (Ir(192)) and 3D conformal external beam radiotherapy in patients with localized prostate cancer.

METHODS

A total of 442 patients with localized prostate cancer underwent combined radiotherapy with interstitial brachytherapy with Ir(192) and 3D conformal external beam radiotherapy between December 1992 and March 2001. Patients underwent laparoscopic pelvic lymph node dissection to exclude patients with lymphatic involvement. Iridium 192 was delivered twice with a one-week interval in afterloading technique. 247 patients (56%) had clinical T3 disease and 128 patients (29%) had an initial PSA of more than 20 ng/ml. Progression was defined as biochemical failure according to ASTRO criteria. Patients were divided according to pretreatment variables that independently affected prostate-specific antigen (PSA) relapse-free survival in three risk groups. Low risk was defined as cT1c-cT2 and G1-G2 and PSA<10 ng/ml (n=94). Intermediate risk included patients with cT1c-cT2 and G1-G2 and PSA between 10 and 20 ng/ml (n=53). High risk group patients were cT3 or G3 or PSA>20 ng/ml (n=295).

RESULTS

Median follow-up was 5 years. Late grade 3-4 complications according to RTOG/EORTC criteria occurred in 50 patients (11%). The initial PSA value decreased from median 11.8 ng/ml to 0.98 ng/ml 12 months after treatment, to 0.3 ng/ml after 60 months and to 0.1 ng/ml 10 years after therapy. 53% of the patients (n=235) reached a PSA nadir of 0.5 ng/ml. 66 patients (15%) had a local recurrence, 54 (12%) developed systemic disease and 12 (3%) had both local and systemic failure. The progression free survival rate was 65% at 5-year follow-up. Five-year progression free survival was 81% in the low risk group, 65% in the intermediate risk group and 59% in the high risk group. Five-year overall survival was 87% and 5-year disease specific survival 94%. Initial PSA value, risk group and age were significantly related to progression free survival.

CONCLUSIONS

Combined HDR brachytherapy with Iridium 192 is an alternative treatment option for patients with localized prostate cancer. Initial PSA value, risk group, and age are important prognostic factors for progression free survival.