35 Background: SBRT is an emerging treatment for prostate cancer, but long-term reporting remains sparse. We present a prospective Phase II trial with 90% treated in community facilities. Methods: 14 institutions enrolled 259 patients - 112 low-risk; 147 intermediate-risk. The regimen emulated a high-dose rate brachytherapy (HDR) regimen - 38 Gy/4 fractions delivered by robotic SBRT. Androgen deprivation therapy was not allowed. HDR-like heterogeneous prostate dosing was used (Dmax >57 Gy). Toxicities were assessed by CTCAE v3.0 and quality of life assessed by Expanded Prostate Cancer Index Composite (EPIC). Biochemical recurrence was defined by Phoenix criteria. Results: Median follow-up is 5 years. 5-yr Grade 2 GU toxicity was 13.7% and GI toxicity 4.5%, with Grade 3 rates of 3% (GU) and 0% (GI) (one Gd 4 GU event). 5-yr median PSA was 0.1 ng/mL with further subsequent decrease (7 y = 0.035 ng/mL). 5-yr biochemical disease-free survival (bDFS) = 100% for low-risk and 88.5% for int-risk. 6 patients developed distant metastasis and one died of disease. Median EPIC GU obstruction and GI scores were similar at baseline vs. 5 years. 2% of patients had baseline GU incontinence requiring pad use vs 10% at 5 yrs. Of baseline potent men, 46% remained so at 5 yrs (66.7% for those age ≤65 vs. 37.1% age >65 at treatment). Conclusions: This is the first report of 5-year median follow-up outcomes post heterogeneous dosing SBRT for early prostate cancer. This treatment produces a low PSA nadir vs other forms of radiotherapy, with a favorable long-term result that appears reproducible in the community. Clinical trial information: 00643617. [Table: see text]
Stereotactic body radiation therapy is an emerging treatment for prostate cancer (PC), with potential biological and oncologic advantages. A well-established radiation dosing schedule (38 Gy in 4 fractions) has shown excellent long-term efficacy in high-dose-rate (HDR) brachytherapy. To report 5-yr efficacy, toxicity, and quality-of-life (QOL) outcomes of a novel 4-d SBRT regimen. This was a single-arm prospective phase 2 trial involving 259 patients with low- or intermediate-risk PC treated at 18 US centers from December 2007 to February 2012. The median follow-up was 5 yr (interquartile range 37–85 mo). SBRT with 38 Gy in four fractions; radiation plans mimicked HDR brachytherapy dosimetry. We measured freedom from biochemical recurrence (BCR) and assessed toxicities using the Common Terminology Criteria for Adverse Events v3.0 and QOL using the Expanded Prostate Cancer Index Composite. The 5-yr BCR-free rates were 100% and 88.5% for patients with low- and intermediate-risk PC, respectively. The cumulative 5-yr grade 2, 3, and 4 toxicity rates were 12.4%, 1.9%, and 0.4% for urinary, and 3.4%, 0%, and 0% for gastrointestinal toxicities, respectively. The median baseline prostate-specific antigen (PSA) level of 5.12 ng/ml decreased to 0.1 ng/ml by ≥42 mo. QOL scores decreased at 1 mo but returned to baseline by 6 mo, with a later decline (≥24 mo) in the urinary continence domain (pad use was 2% at baseline and 10% at 5 yr), and lower sexual potency over time. Comparative outcomes versus other types of radiotherapy are difficult because the trial was not randomized. This regimen yields a high rate of BCR-free survival, with a very low median PSA nadir suggesting prostate ablation. For properly selected patients with low- or intermediate-risk PC who choose SBRT, this treatment regimen is effective. This potent four-treatment stereotactic body radiotherapy regimen appears to be effective for patients with early prostate cancer.
We report our single-institution stereotactic body radiation therapy (SBRT) experience on stage I renal cancer with prospectively collected toxicity and efficacy data.
