Real-Time Integration of MR Imaging for Prostate High-Dose-Rate Brachytherapy Using 3D Slicer

Abstract

Purpose: To report acute (!3 months) and late (O6 months) genitourinary (GU), and gastrointestinal (GI) toxicities, and erectile dysfunction (ED) in patients treated with inverse-planned selective HDR brachytherapy boost to the dominant intraprostatic lesion (DIL) defined with magnetic resonance spectroscopy (MRS). Materials and Methods: We analyzed data prospectively collected from 20 patients treated in 2010-2011 for localized intermediate-risk prostate adenocarcinoma. All patients had an MRI/MRS to define the DIL before treatment. Afterward, they received external beam pelvic radiation (40-44 Gy in 20-22 fractions) followed by HDR (Ir) brachytherapy boost. The boost dose was 15 Gy in one fraction to the whole gland with simultaneous 3 Gy selective boost to the DIL (total of 18 Gy to DIL). All patients were planned with inverse-planning simulated annealing (IPSA). Thereafter, IPSS, International Index of Erectile Dysfunction-5 (IIEF5) and GI toxicities questionnaires were completed prospectively every three months at a followup visits. Results: The median age was 65.5 years. The median followup was 23.6 months. Fifty-five percent of the patients had clinical stage T1c, 25 % T2a, 15% T2b and 5% T2c. All patients were Gleason score (GS) 7. The pretreatment PSA was 0-5 ng/mL in 30%, 5-10 ng/mL in 60% and 10-15 ng/mL in 10% of the patients, respectively. No patients received antiandrogen therapy. The average IPSS at baseline and 1, 4 and 12 months was 6.57/35, 10.94/35, 7.32/35 and 8.47/35, respectively. At 3 months we observed a decrease of IIEF5 score from baseline of -4.45 (þ/-0.22) and -3.31 (þ/-0.39) atO6 months. At 3 months 50% of patients presented no GI symptoms and 50% occasional GI symptoms. No patients presented severe GI toxicityO6 months. Conclusions: Selective DIL image-guided (MRS) HDR brachytherapy boost in intermediate-risk cancer, is feasible with acceptable acute and late GU and GI toxicity at the price of decreasing IIEF5 score. Longer followup is necessary to evaluate tumor control.