Stereotactic hypofracionated radiotherapy for prostate cancer patients.

Abstract

e16097 Background: 3D conformal radiotherapy (78Gy in 2Gy per fraction) is the standard treatment for prostate cancer patients. It is a very long treatment, not comfortable both for patients and radiotherapy departments. Stereotactic radiotherapy has recently been recognized as an alternative technique. Prostate cancer has probably a low α/β ratio (1.5Gy) and 33.5Gy in 5 fractions has the predicted efficacy of 78Gy in 39 fractions. The objective of the study was to investigate the effectiveness and safety of stereotactic radiotherapy for localized prostate cancer. Methods: This is a prospective one-center clinical study. The treatment was done with IMRT. PTV received 33.5Gy in 5 fractions twice a week. Three gold fiducial markers were placed in the prostate under transrectal ultrasound guidance for image-guided positioning and motion tracking. Treatment planning CT and MRI scans were performed. IMRT plans were done. Before each treatment MV Cone Beam CT and portal imagines for markers were performed. Results: In this analysis 32 patients were included (age 65-83 years, median 73 years) with localized low- and intermediate-risk (according to NCCN) adenocarcinoma of prostate T2-T3N0M0. Combined Gleason scores were 5 to 7, the prostate-specific antigen (PSA) was 4.7-20.0ng/ml (median 10.2ng/ml). The median prostate volume calculated during treatment planning (on CT and MR) was 40.5cc (15.8cc to 113.6cc). Acute genitourinary toxicity Grade 1–2 was observed in about 50% patients and only Grade 1 acute gastrointestinal toxicity in 25% patients. No Grade 3 or higher toxicity was reported. Only 3 patients reported rectal bleeding after radiotherapy (Grade 1 late toxicity). PSA level were systematically decreased to 1.08ng/ml 3 months, 0.91ng/ml 6 months and 0.56ng/ml 9 months after treatment end. Conclusions: Stereotactic hypofractionated radiotherapy for prostate cancer patients is an effective and safe treatment in short term analysis.