Dose escalation to dominant intraprostatic lesions with MRI-transrectal ultrasound fusion High-Dose-Rate prostate brachytherapy. Prospective phase II trial

Abstract

Background and purpose: To demonstrate the feasibility, safety and effectiveness of dose escalation to intraprostatic lesions with MRI-transrectal ultrasound fusion High-Dose-Rate (HDR) brachytherapy.

Materials and methods: 15 patients with intermediate-high risk prostate cancer and visible dominant intra-prostatic nodule on mpMRI have been treated. The treatment consisted of combined MRI-TRUS fusion HDR-brachytherapy (1 fraction of 1500cGy) and hypofractionated external beam (3750cGy in 15 fractions). A dose of 1875Gy was delivered to at least 98% of the DIL volume.

Results: Median prostate volume was 23.8cc; median number of needles was 16 (13-18). Dose escalation to DIL was feasible in 14/15 patients (93%) without violating dosimetric constraints and 1 patient presented a minimal deviation of dosimetric restrictions. With a median follow-up of 18months (17-24), none of the patients developed acute urinary retention or grade ⩾3 toxicity. In addition to standard PSA follow-up, response has been assessed by mpMRI at 12months. All patients presented adequate morphological responses on anatomical and functional sequences.

Conclusions: HDR brachytherapy using MRI-transrectal ultrasound fusion for image guidance is a suitable technique for partial prostate dose escalation. Tolerance and toxicity profiles are excellent and results are encouraging in terms of biochemical, morphological and functional response.

Keywords: Dominant intraprostatic lesion; Dose escalation; High-Dose-Rate brachytherapy; Prostate cancer.