Prostate cancer: biological dose considerations and constraints in tele- and brachytherapy

In Europe, prostate cancer is the most frequently diagnosed malignancy in men. Radiotherapy is an effective treatment option, which, however, is inevitably associated with exposure of rectum and urinary bladder to significant doses. Hence, radiobiological parameters of both prostate tumors and normal tissues to be considered in prescribing treatment, such as the effect of overall treatment time, dose fractionation and exposed volume, will be discussed in this review. For the treatment of localized prostate tumors (T1-2N0M0, G1-2, Gleason<7, PSA<10 ng/ml), external beam radiotherapy (EBRT) or low dose-rate brachytherapy (LDRBT) is recommended. With conventional EBRT, 70-74 Gy in 1.8-2.0 Gy fractions are applied within 6-7 weeks. LDRBT is administered with 125-I or 103-Pd to doses of 125-145 Gy in several weeks. Tumors with unfavourable prognostic factors and advanced tumors (T1-2N0M0, G3, Gleason > 6, PSA>20; T3) are treated with conformal EBRT (5 x 1.8-2.0 Gy/week) to 74-78 Gy, or with a combination of EBRT (30-50 Gy) and HDRBT (12-30 Gy/2-4 F) to total doses of 58-80 Gy. (orig.)