Curative radiotherapy of localized prostate cancer. Treatment methods and results

Abstract

Radiation oncology has undergone rapid technical development during the last few years. The further development of treatment planning systems and treatment machines had a major impact on the improvement of radiation therapy results in prostate cancer. This paper presents different treatment modalities and results. Currently available are three-dimensional conformal radiation, intensity modulated radiation therapy (IMRT), high dose rate brachytherapy, and low dose rate brachytherapy (seed implantation). All modalities offer the possibility for dose escalation, which is essential for curative treatment. Dose escalation using these techniques makes it possible to reduce the dose for the surrounding organs at risk. Three-dimensional conformal radiation therapy can be delivered with doses up to 78 Gy. The biochemical control rate is up to 90% depending on the risk factors T stage, initial PSA, and Gleason score. The incidence of late side effects is <10%. IMRT is a newer modality for percutaneous radiotherapy. By individual dose modification in the treatment fields, doses >80 Gy can be delivered in small treatment volumes. Treatment has to be highly precise to avoid dose peaks in the organs at risk, i.e., rectum and bladder. The preliminary data for remission and toxicity rates are promising, but it is too early for final conclusions. For cases with high-risk factors such as PSA >10 ng/ml, Gleason score >6, and stage T3, percutaneous radiation can be combined with neoadjuvant or adjuvant hormonal treatment. Randomized trials showed an improvement of the results in favor of combined treatment. HDR brachytherapy in combination with external radiation is a good option for dose escalation in patients with locally advanced tumors and/or other high-risk factors. The biochemical control rates are between 60 and 84%, late effects occur in less than 10%. Seed implantation (LDR brachytherapy) as sole treatment is indicated for prognostically favorable situations (PSA <10 ng/ml, Gleason score < or =6, and T1c or T2a tumors). The biochemical control rates are between 80 and 90%. Toxicity consists of urine retention and proctitis, occurring in 10-20% of the patients.