A Pooled Analysis of Biochemical Failure in Intermediate-risk Prostate Cancer Following Definitive Stereotactic Body Radiotherapy (SBRT) or High-Dose-Rate Brachytherapy (HDR-B) Monotherapy.
To investigate biochemical relapse-free survival (BRFS) in men with National Comprehensive Cancer Network-defined intermediate-risk prostate cancer (PC) treated with either stereotactic body radiotherapy (SBRT) or high-dose-rate brachytherapy (HDR-B) monotherapy.



A retrospective, multi-institutional analysis of 437 patients with intermediate-risk PC treated with SBRT (N=300) or HDR-B (N=137) was performed. Men who underwent SBRT were treated to 35 to 40 Gy in 4 to 5 fractions. A total of 95.6% who underwent HDR-B were treated to 42 Gy in 6 fractions. Baseline patient characteristics were compared using a T test for continuous variables and the Mantel-Haenszel χ metric or Fisher exact test for categorical variables. Kaplan-Meier curves were generated to estimate 5-year actuarial BRFS. Multivariate analysis using a Cox proportional-hazards model was used to evaluate factors associated with biochemical failure.



The mean age at diagnosis was 68.4 (SD±7.8) years. T-category was T1 in 63.6% and T2 in 36.4%. Mean initial prostate-specific antigen was 7.4 (SD±3.4) ng/mL. Biopsy Gleason score was ≤3+4 in 82.8% and 4+3 in 17.2%. At a median of 4.1 years of follow-up, the BRFS rate (Phoenix definition) was 96.3%, with no difference when stratifying by treatment modality or biologically equivalent dose (BED1.5). On multivariate analysis, age (hazard ratio 1.08, P=0.04) and biopsy Gleason score (hazard ratio 2.48, P=0.03) were significant predictors of BRFS.



With a median follow-up period of 4 years, SBRT and HDR-B monotherapy provide excellent BRFS in intermediate-risk PC. Longer-term follow-up is necessary to determine the ultimate efficacy of these hypofractionated approaches, but they appear promising relative to standard fractionation outcomes.
Department of Radiation Oncology, UCLA Medical Center, Los Angeles.
John V
JV
Hegde
Department of Radiation Medicine, Georgetown University Medical Center, Washington, DC.
Sean P
SP
Collins
Division of Genesis Healthcare Partners Inc., CyberKnife Centers of San Diego Inc., San Diego, CA.
Donald B
DB
Fuller
Department of Radiation Oncology, UCLA Medical Center, Los Angeles.
Christopher R
CR
King
Department of Radiation Oncology, UCLA Medical Center, Los Angeles.
D Jeffrey
DJ
Demanes
Department of Radiation Oncology, UCLA Medical Center, Los Angeles.
Pin-Chieh
PC
Wang
Department of Radiation Oncology, UCLA Medical Center, Los Angeles.
Patrick A
PA
Kupelian
Department of Radiation Oncology, UCLA Medical Center, Los Angeles.
Michael L
ML
Steinberg
Department of Radiation Oncology, UCLA Medical Center, Los Angeles.
Mitchell
M
Kamrava
D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects*; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D060787:Neoplasm Grading; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000209:etiology; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D016634:Radiosurgery / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D015996:Survival Rate