Stereotactic Body Radiotherapy for Clinically Localized Prostate Cancer: Toxicity and Biochemical Disease-Free Outcomes from a Multi-Institutional Patient Registry

Abstract

Objectives: To report on initial patient characteristics, treatment practices, toxicity, and early biochemical disease-free survival (bDFS) of localized prostate cancer treated with stereotactic body radiotherapy (SBRT) and enrolled in the RSSearch® Patient Registry.Methods: A retrospective analysis was conducted on patients with clinically localized prostate cancer enrolled in RSSearch® from June 2006 - January 2015. Patients were classified as low-risk (PSA ≤ 10 ng/ml, T1c-T2a, Gleason score ≤ 6), intermediate-risk (PSA 10.1 - 20 ng/ml, T2b-T2c, or Gleason 7), or high-risk (PSA > 20 ng/ml, T3 or Gleason ≥ 8). Toxicity was reported using Common Toxicity Criteria for Adverse Events, version 3. Biochemical failure was assessed using the Phoenix definition (nadir + 2 ng/ml). The Kaplan-Meier analysis was used to calculate bDFS and association of patient and tumor characteristics with the use of SBRT.Results: Four hundred thirty-seven patients (189 low, 215 intermediate, and 33 high-risk) at a median of 69 years (range: 48-88) received SBRT at 17 centers. Seventy-eight percent of patients received 36.25 Gy/5 fractions, 13% received 37 Gy/5 fractions, 6% received 35 Gy/5 fractions, 3% received 38 Gy/4 fractions, and 5% received a boost dose of 19.5-29 Gy following external beam radiation therapy. Median follow-up was 20 months (range: 1–64 months). Genitourinary (GU) and gastrointestinal (GI) toxicities were minimal, with no acute or late Grade 3+ GU or GI toxicity. Late Grade 1 and 2 urinary frequency was 25% and 8%. Late Grade 1 and 2 proctitis was 3% and 2%. Median PSA decreased from 5.8 ng/ml (range: 0.3-43) to 0.88, 0.4, and 0.3 ng/ml at one, two, and three years. Two-year bDFS for all patients was 96.1%. Two-year bDFS was 99.0%, 94.5%, and 89.8% for low, intermediate, and high-risk patients (p < 0.0001). Two-year bDFS was 99.2%, 93.2%, and 90.4% for Gleason ≤ 6, Gleason 7, and Gleason ≥ 8 (p < 0.0001). Two-year bDFS was 96.4%, 97.2%, and 62.5% for PSA ≤ 10 ng/ml, PSA 10.1 - 20 ng/ml, and PSA > 20 ng/ml (p < 0.0001). Clinical T Stage was not significantly associated with bDFS. Conclusions: Early disease outcomes of SBRT for the treatment of clinically localized prostate cancer from a multicenter patient registry compare favorably with reports from single institutions. Acute and late GU and GI toxicities were minimal, and PSA response to SBRT was highly encouraging. Continued accrual and follow-up will be necessary to confirm long-term results.

Stereotactic Body Radiation Therapy for Localized Prostate Cancer: A Systematic Review and Meta-Analysis of Over 6,000 Patients Treated On Prospective Studies

“…W.C.J and D.E.S independently extracted data from the 38 identified studies. [37][38][39][40][41][42][43][44][45][46][47][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68] Variables extracted included study and patient-level characteristics, such as study type, phase of trial, sample size, dose per fraction, fraction number, duration of follow-up, age, clinical tumor stage, baseline prostate-specific antigen, National Comprehensive Cancer Network (NCCN) 69 risk group of enrolled patients, receipt of androgen-deprivation therapy (ADT), bRFS, physician-reported toxicity, and patientreported QOL, if reported. Individual patient data was not used.…”

First Australian experience of treating localised prostate cancer patients with CyberKnife stereotactic radiotherapy: early PSA response, acute toxicity and quality of life

“…Data collection close‐out date was 30 September 2016. Every patient treated with CyberKnife at our centre is also invited to enrol in the International RSSearch ® Patient Registry (http://ClinicalTrials.gov Identifier: ), and as such some of the data presented in this study have been reported in part as a pooled analysis with other centres . All patients had clinically localised biopsy‐proven prostate cancer, confirmed by computed tomography (CT) and bone scan.…”

“…Every patient treated with CyberKnife at our centre is also invited to enrol in the International RSSearch â Patient Registry (ClinicalTrials.gov Identifier: NCT01885299), and as such some of the data presented in this study have been reported in part as a pooled analysis with other centres. 3 All patients had clinically localised biopsy-proven prostate cancer, confirmed by computed tomography (CT) and bone scan. Patients were stratified into D'Amico risk groups (low risk: PSA < 10, Gleason sum of 6 and clinical stage T1c-T2a; intermediate risk: PSA 10-20, Gleason sum of 7 or clinical stage T2b; high risk: PSA > 20, Gleason sum of 8-10 or clinical stage T2c or higher).…”

Stereotactic radiotherapy for prostate cancer: A review and future directions

“…Davis et al[28] analyzed outcomes for a total of 437 localized prostate cancer patients treated with SBRT at one of seventeen centers in the United States and Australia. Patients were enrolled between 2006 and 2015 and all risk categories were represented.…”