Role of radiotherapy in the treatment of prostate carcinoma

The main therapeutic approaches to the localized prostate cancer include prostatectomy and radiation therapy. Conclusive, large randomized trials comparing these two methods are not available, however indirect comparisons show their similar efficacy. The toxicity profiles of both methods are different (sexual impotency and urinary disorders after surgery, and gastro-intestinal reactions after radiation therapy). Radiation therapy for prostate cancer includes external beam irradiation and brachytherapy (intraprostatic implants of radioactive sources). Conventional radiotherapy is effective at early stages of the disease (15-year survival probability of about 85% for T1 tumors), whereas these figures for T2-T3 tumors are in the range of 65-68% and 44-75%, respectively. Conventional radiotherapy with multiple-field technique does not allow for the administration of more than 64-66 Gy, mainly due to the dose-limiting rectal toxicity. Recent improvements in diagnostics (nuclear magnetic resonance, transrectal ultrasound, intraoperative ultrasound, positron emission tomography) and radiation techniques allow for precise identification of tumor extension and more localized delivery of radiation therapy. Three-dimensional conformal radiotherapy (3-D CRT) and intensity modulation irradiation (IMRT) allow for further dose escalation within the target volume and sparing the nearby normal tissues. This might be of particular relevance, given the clear dose-response relationship demonstrated in prostate cancer. Brachytherapy is recommended for low risk early tumors confined to the prostate (T1-2b, PSA <10 ng/ml, Gleason score <6) and can be a valid alternative to surgery or external beam irradiation, given its better toxicity profile.