Propensity-Weighted Survival Analysis of SBRT vs. Conventional Radiotherapy in Unfavorable Intermediate-Risk Prostate Cancer

• Type of Material: Article
• Authors: Neal Andruska, Washington University in St. Louis; Benjamin Fischer-Valuck, Emory University; Temitope Agabalogun, Washington University in St. Louis; Rubern Carmona, University of Miami; Randal J Brenneman, Washington University in St. Louis; Yi Huang, Washington University in St. Louis; Hiram A Gay, Washington University in St. Louis; Jeff M Michalski, Washington University in St. Louis; Brian C Baumann, Washington University in St. Louis
• Language: English
• Date: 2022-04-01
• Publisher: CIG MEDIA GROUP, LP
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2021 Elsevier Inc. All rights reserved.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.clgc.2021.11.012
• Title of Journal or Parent Work: CLINICAL GENITOURINARY CANCER
• Volume: 20
• Issue: 2
• Start Page: 123
• End Page: 131
• Grant/Funding Information: The work for this report was supported by institutional funds from the Departments of Radiation Oncology and Siteman Cancer Center at Washington University/Barnes Jewish Hospital in St Louis. BCB is funded through an NCI Cancer Clinical Investigator Team Leadership Award (CCITLA), P30 CA091842-20S2.
• Keywords: Oncology; Urology & Nephrology; Science & Technology; Hypofractionated radiotherapy; External beam radiation therapy; CONSORTIUM; THERAPY; ALPHA/BETA RATIO; Ultra-hypofractionated radiotherapy; National Cancer Database; Unfavorable intermediate-risk; Life Sciences & Biomedicine; STEREOTACTIC BODY RADIOTHERAPY; Stereotactic body radiation therapy

Abstract

Background: Prostate stereotactic body radiotherapy (SBRT), which delivers high-dose precision treatment in ≤5 fractions, is a shorter, more convenient, and less expensive alternative to conventionally fractionated radiotherapy (CRFT; ∼44 fractions) or moderately hypofractionated radiotherapy (MFRT; 20-28 fractions). SBRT has not been widely adopted but may have radiobiologic advantages over CFRT/MFRT. We hypothesized that SBRT would be associated with improved overall survival (OS) versus CFRT or MFRT ± androgen deprivation therapy (ADT) for unfavorable-intermediate-risk prostate cancer (UIR-PCa). Methods: Men with UIR-PCa treated with SBRT (35-40Gy in ≤5 fractions) or biologically equivalent doses of CFRT (72-86.4Gy in 1.8-2.0Gy/fraction) or MRFT (≥60Gy in 2.4-3.2Gy/fraction; biologically effective doses ≥120) were identified in the National Cancer Database (NCDB). Unweighted and propensity-weighted multivariable Cox analysis (MVA) was used to compare OS hazard ratios. Results: Of 28,028 men with UIR-PCa who received CFRT with (n = 12,872) or without ADT (n = 12,984); MFRT with (n = 251) or without ADT (n = 281); and SBRT with (n = 212) or without ADT (n = 1,428) were identified. Relative to CFRT without ADT, CFRT+ ADT (HR 0.92, 95% CI 0.87-0.97, P = .002) and SBRT without ADT (HR 0.74, 95% CI 0.61-0.89, P = .002) were both associated with improved OS on MVA. Relative to CFRT+ADT, SBRT without ADT correlated with improved OS on MVA (HR:0.81, 95% CI 0.67-0.99, P = .04). Propensity-weighted MVA demonstrated that SBRT (HR:0.80, 95% CI 0.65-0.98, P = .036) and ADT (HR:0.91, 95% CI 0.86-0.97, P = .002) correlated with improved OS. SBRT was not associated with improved OS versus MFRT. Conclusion: SBRT, which offers a cheaper and shorter treatment course that mitigates COVID-19 exposure, was associated with improved OS versus CFRT for UIR-PCa. These results confirm guideline-based recommendations that SBRT is a viable option for UIR prostate cancer. The results from this large retrospective study require further validation in clinical trials.