Dose-Intensified Stereotactic Ablative Radiation for Localized Prostate Cancer

Lily Chen; Bhavani S Gannavarapu; Neil B Desai; Michael R Folkert; Michael Dohopolski; Ang Gao; Chul Ahn; Jeffrey Cadeddu; Aditya Bagrodia; Solomon Woldu; Ganesh V Raj; Claus Roehrborn; Yair Lotan; Robert D Timmerman; Aurelie Garant; Raquibul Hannan

doi:10.3389/fonc.2022.779182

Dose-Intensified Stereotactic Ablative Radiation for Localized Prostate Cancer

Front Oncol. 2022 Feb 21:12:779182. doi: 10.3389/fonc.2022.779182. eCollection 2022.

Authors

Affiliations

¹ School of Medicine, The University of Texas Rio Grande Valley, Edinburg, TX, United States.
² Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States.
³ Department of Population and Data Sciences, University of Texas (UT) Southwestern Medical Center, Dallas, TX, United States.
⁴ Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX, United States.

Abstract

Purpose: Stereotactic ablative radiation (SAbR) has been increasingly used in prostate cancer (PCa) given its convenience and cost efficacy. Optimal doses remain poorly defined with limited prospective comparative trials and long-term safety/efficacy data at higher dose levels. We analyzed toxicity and outcomes for SAbR in men with localized PCa at escalated 45 Gy in 5 fractions.

Methods and materials: This study retrospectively analyzed men from 2015 to 2019 with PCa who received linear-accelerator-based SAbR to 45 Gy in 5 fractions, along with perirectal hydrogel spacer, fiducial placement, and MRI-based planning. Disease control outcomes were calculated from end of treatment. Minimally important difference (MID) assessing patient-reported quality of life was defined as greater than a one-half standard deviation increase in American Urological Association (AUA) symptom score after SAbR.

Results: Two-hundred and forty-nine (249) low-, intermediate-, and high-risk PCa patients with median follow-up of 14.9 months for clinical toxicity were included. Acute urinary grade II toxicity occurred in 20.4% of patients. Acute grade II GI toxicity occurred in 7.3% of patients. For follow-up > 2 years (n = 69), late GU and GI grade ≥III toxicity occurred in 5.8% and 1.5% of patients, respectively. MID was evident in 31.8%, 23.4%, 35.8%, 37.0%, 33.3%, and 26.7% of patients at 3, 6, 12, 24, 36, and 48 months, respectively. The median follow-up for biochemical recurrence was 22.6 months with biochemical failure-free survival of 100% at 1 year (n = 226) and 98.7% for years 2 (n = 113) and 3 (n = 54).

Conclusions: SAbR for PCa at 45 Gy in 5 fractions shows an encouraging safety profile. Prospective studies with longer follow-up are warranted to establish this dose regimen as standard of care for PCa.

Keywords: SBRT (stereotactic body radiation therapy); dose-intense radiation therapy; gastrointestinal (GI); genitourinary (GU); prostate; prostate cancer; stereotactic ablative radiation (SAbR); toxicity.