PPP04 Presentation Time: 10:57 AM

Purpose

High dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy (EBRT) is a widely accepted treatment for patients with clinically localized prostate cancer. A significant impact on sexual health related quality of life (sHRQoL) is reported in published series. The etiology is probably multifactorial, including baseline factors, trauma and dose to the neurovascular bundles (NVB). Magnetic resonance imaging (MRI) enables the visualization and proper localization of the NVB. Herein we aim to analyze the long-term sHRQoL after MRI-guided whole gland HDR-BT boost for prostate cancer and to assess the impact of the dose to the NVB and other factors on sHRQoL.

Materials and Methods

Sixty-one patients were treated with a single 15 Gy MRI-guided HDR-BT followed by EBRT as part of a prospective phase II trial approved by the local Research Ethic Board (09-0026-C). For this analysis, patients who received over 12 months of androgen deprivation therapy (ADT) and / or patients with a baseline erectile dysfunction were excluded. The left and right NVB were delineated in retrospect on T2-weighted images. Sexual HRQoL was prospectively collected using the expanded prostate index composite (EPIC) questionnaire at baseline, 1month, 3 months, 6 months, 12 months and Q12 monthly thereafter until 60 months. A minimally important difference (MID) was defined as a deterioration of sHRQoL scores at 3 months ≥ 0.5 standard deviation of baseline score. Linear and logistic regression models were used.

Results

Twenty-eight patients met the criteria to be included in this analysis. A short course of ADT was given to 15 patients. the mean baseline sexual HRQOL score was 48.1 (SD=27.1): 41.9 (SD=28.5) for sexual function and 63.8 (SD=37.9) for sexual bother (37.9). At 12, 24, 36 and 60 months the mean sexual score was 37.5 (SD=26.3), 47(SD=24.3), 45.1 (SD=20.4) and 36.8 (SD=29.1), p>0.05. A MID was reported by 50% of patients at 60 months. The mean sHRQoL score at 60 months of patients who had a short course of ADT was 44.1 (SD=27.1) versus 32.2 (SD=31.1), p>0.05.The mean delineated volume of the NVB was 0.35 cc ± 0.12 on the right and 0.36 cc ± 0.13 on the left. The median number of needles used was 18 [interquartile range(IQR):17-19]. The median dose max to the left NVB is 20.9 Gy (17.4-22.8) and to the right NVB is 21.1 Gy (19.0-24.0). the median dose to the penile bulb was 5.4 Gy (4.2-7.8).There was no association found between any of the baseline or dosimetric parameters with the deterioration sHRQoL.

Conclusions

Fifty percent of prostate cancer patients treated with MRI-guided HDR-BT followed by EBRT reported a MID in their sHRQoL at 5 years after . The dose received by the NVB bilaterally was consistently higher than 120% of the prescription dose. A short course of ADT was not associated with a worse sHRQoL score at 5 years. Further studies should focus on using MRI to accurately delineate the NVB and assess the feasibility and impact of limiting the dose to the NVB.