FACTORS INFLUENCING RELAPSE-FREE SURVIVAL IN PROSTATE CANCER PATIENTS AFTER DEFINITIVE RADIOTHERAPY

Purpose: Our purpose is to analyze the effects of several prognostic and therapeutical factors to the PSA relapse free survival in the group of patients who were treated definitively for localized carcinoma of the prostate in the Department of Radiation Oncology at the Marmara University Hospital. Material and Methods: Sixty four patients with clinically localized carcinoma of the prostate who did not have any distant metastases at the time of diagnosis were treated definitively between March 1997 and November 1998 and the data was analysed retrospectively in September 2001. The median age of the patients was 71, median PSA level was 15 ng/ml and median Gleason score was 7 (3-9). Patients received 50 Gy of radiation to the pelvis over a five-week period and an additional prostatic boost or localised prostatic fields to the therapeutic doses of between 60 and 76 Gy. Combined or neoadjuvant androgen supression therapy were given to 47 patients and the other 17 patients did not have any other therapies. The definition of biochemical failure after external beam radiation therapy (EBRT) is three consecutive rises in PSA levels as in the ASTRO concensus guidelines. The median follow-up time is 35 months and the 'PSA relapse free survival' is defined as the time from the first day of EBRT to the time of the first PSA relapse or if there is not any relapse, it's the time to the last PSA follow-up. Results: Fifty months PSA relapse free survival of the whole group and the survival of the patients who were treated with androgen supression therapies and who did not have any other therapies rather than EBRT were 80%, 75% and 85%, respectively (p=0.8). The factors which are determined to affect the PSA relapse free survival statistically were the initial PSA levels (p=0.03), Gleason score (p=0.002) and positive nodal status (p=0.01). The combination of androgen suppression therapy with EBRT concomittantly (p=0.04) affects the relapse free survival of the patients with high risk prognostic factors. The factors for the patients with Gleason scoring greater than 7 and the initial PSA levels greater than 10 are radiation doses and the combination of concomittant androgen suppression therapy. Cox regression analyses revealed that the Gleason score was the factor affecting biochemical relapse free survival statistically. Conclusion: Combined androgen suppression therapy for prostatic carcinoma patients with high risk prognostic factors seems to be superior to the patients treated with only EBRT. But the optimal timing of androgen suppression and the sequence is not known and the results of prospective randomised studies are awaited.

Keywords: prostatic adenocarcinoma, radiation therapy