Toxicity and quality of life report of a phase II study of stereotactic body radiotherapy (SBRT) for low and intermediate risk prostate cancer.

BACKGROUND: Clinical data indicates that delivery of larger daily doses of radiation may improve the therapeutic ratio for prostate cancer compared to conventional fractionation. A phase II study of stereotactic body radiotherapy with real-time motion management and daily plan re-optimization for low to intermediate risk prostate cancer was undertaken to evaluate this hypothesis. This report details the toxicity and quality of life following treatment. METHODS: From 2009 to 2013, 60 patients with T1-T2c prostate cancer with a Gleason score of 6 and PSA ≤ 15 or Gleason score of 7 and PSA ≤ 10 were enrolled. Patients with nodal metastases, an American Urological Association symptom score > 18, or gland size > 100 g were not eligible. Patients were treated to 37 Gy in 5 fractions. Early and late genitourinary and gastrointestinal toxicity were graded based on NCI CTCAE v4.0 and quality of life was assessed by the American Urological Association symptom score, International Index of Erectile Function, and Expanded Prostate cancer Index Composite Short Form up to 36 months after treatment. RESULTS: After a median follow-up of 27.6 months, no grade 3 or greater genitourinary toxicity was observed. Four patients (6.7%) reported a late grade 2 genitourinary toxicity. One patient (1.7%) reported a late grade 3 gastrointestinal toxicity. Five patients (8.3%) developed a late grade 2 gastrointestinal toxicity. The median American Urological Association symptom score increased from 4.5 prior to treatment to 11 while on treatment (p < 0.01), but was 5 at 36 months post-treatment (p = 0.65). Median International Index of Erectile Function scores decreased from 19 to 17 over the course of follow-up (p < 0.01). Only median scores within the Expanded Prostate Cancer Index Composite Short Form sexual domain were significantly decreased at 36 months post-treatment (67.9 vs 45.2, p = 0.02). There was no significant difference in median score within the urinary, bowel, or hormonal domains at 36 months of follow-up. CONCLUSIONS: Stereotactic body radiotherapy for low to intermediate risk prostate cancer is well tolerated with limited toxicity or decrease in quality of life. Longer follow-up is necessary to assess the efficacy of treatment. TRIAL REGISTRATION: Clinicaltrials.gov NCT00941915 Registered 17 June 2009.

Radiation dose to the neurovascular bundles or penile bulb does not predict erectile dysfunction after prostate brachytherapy.

PURPOSE: To examine the relationship between calculated doses to the neurovascular bundles (NVBs) and the penile bulb (PB) and the development of erectile dysfunction (ED) after low-dose-rate prostate brachytherapy (LDRPB) alone. METHODS AND MATERIALS: Between September 1997 and June 1999, 84 men were treated with LDRPB alone. Inclusion criteria for this study were (1) no ED according to a self-administered questionnaire before PB, (2) treatment with PB alone (125I; 144 Gy), (3) postimplant CT scan of the prostate 1 month after PB, and (4) minimum of 24 months of continuous follow-up. Fifty men met all inclusion criteria. ED was assessed by a self-administered questionnaire completed before and at each follow-up visit after LDRPB. Radiation doses to the NVB and PB were calculated on the basis of axial postimplant CT images. Multiple variables (patient-related and dosimetric quantifiers) that may predict for the development of ED were examined by univariate analysis. RESULTS: Thirty of the 50 men (60%) were potent at last follow-up. The only patient-related variable that predicted for the development of ED was patient age (<65 vs. >65 years; p=0.03). The calculated mean maximum doses to the NVB and PB were 684 Gy (range, 195-1277 Gy) and 498 Gy (range, 44-971 Gy), respectively. The mean calculated doses to 50% of the NVB and PB were 158 Gy (range, 76-240 Gy) and 43 Gy (range, 19-101 Gy), respectively. The calculated mean maximum, mean minimum, and mean doses to 50% of the NVB or PB did not differ between those men who developed ED and those men who did not develop ED. None of the dosimetric variables examined predicted the development of ED after LDRPB. CONCLUSIONS: In our experience, higher calculated doses to the NVB or PB are not associated with ED after LDRPB.