External beam radiotherapy for prostate cancer

Abstract

External beam radiotherapy (EBRT) is a well established curative treatment for prostate cancer. Retrospective studies demonstrate similar biochemical recurrence free survival rates of radical prostatectomy and EBRT for patients in comparable prognostic subgroups, so that patient information should particularly include the respective toxicity spectrum. In principle, EBRT can be offered to every patient without distant metastases and a life expectancy of at least 5-10 years. The decision involves the selection of a suitable technique, dose, target volume and the option of a combination with antiandrogen therapy. Prospective randomized studies showed the advantage of a dose escalation up to total doses of 76-78Gy concerning biochemical tumor control; additionally concerning disease-specific survival for high risk patients. Other randomized trials demonstrated a survival benefit for patients with locally advanced or high risk cancers who received an additional adjuvant antiandrogen therapy to EBRT. Based on the results of randomized studies, an adjuvant post-prostatectomy EBRT of the prostatic fossa with doses in the range of 60-66 Gy can be recommended in case of positive surgical margins or pT3 tumors - reducing the risk of metastases and increasing survival. In case of a biochemical (or macroscopic) recurrence after radical prostatectomy, EBRT is the only curative treatment option for the patient - favorable prognostic factors are low pre-EBRT PSA (prostate-specific antigen) levels, long PSA doubling doubling time, long interval between prostatectomy and recurrence, low Gleason score, positive margins and an absent seminal vesicle involvement. Total doses of at least 70 Gy should be administered in case of macroscopic recurrences, but the curative chances are considerably lower in comparison to a biochemical recurrence alone.