Multi-Institutional Outcomes of Stereotactic Magnetic Resonance Image Guided Adaptive Radiation Therapy With a Median Biologically Effective Dose of 100 Gy10 for Non-bone Oligometastases

Tugce Kutuk; Robert Herrera; Teuta Z Mustafayev; Gorkem Gungor; Gamze Ugurluer; Banu Atalar; Rupesh Kotecha; Matthew D Hall; Muni Rubens; Kathryn E Mittauer; Jessika A Contreras; James McCulloch; Noah S Kalman; Diane Alvarez; Tino Romaguera; Alonso N Gutierrez; Jacklyn Garcia; Adeel Kaiser; Minesh P Mehta; Enis Ozyar; Michael D Chuong

doi:10.1016/j.adro.2022.100978

Multi-Institutional Outcomes of Stereotactic Magnetic Resonance Image Guided Adaptive Radiation Therapy With a Median Biologically Effective Dose of 100 Gy₁₀ for Non-bone Oligometastases

Adv Radiat Oncol. 2022 Apr 25;7(6):100978. doi: 10.1016/j.adro.2022.100978. eCollection 2022 Nov-Dec.

Authors

Tugce Kutuk¹, Robert Herrera¹, Teuta Z Mustafayev², Gorkem Gungor², Gamze Ugurluer², Banu Atalar², Rupesh Kotecha^{1

3}, Matthew D Hall^{1

3}, Muni Rubens⁴, Kathryn E Mittauer^{1

3}, Jessika A Contreras^{1

3}, James McCulloch^{1

3}, Noah S Kalman^{1

3}, Diane Alvarez^{1

3}, Tino Romaguera^{1

3}, Alonso N Gutierrez^{1

3}, Jacklyn Garcia⁵, Adeel Kaiser^{1

3}, Minesh P Mehta^{1

3}, Enis Ozyar², Michael D Chuong^{1

3}

Affiliations

¹ Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida.
² Department of Radiation Oncology, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey.
³ Department of Radiation Oncology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida.
⁴ Department of Clinical Informatics, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida.
⁵ Herbert Wertheim College of Medicine, Florida International University, Miami, Florida.

Abstract

Purpose: Randomized data show a survival benefit of stereotactic ablative body radiation therapy in selected patients with oligometastases (OM). Stereotactic magnetic resonance guided adaptive radiation therapy (SMART) may facilitate the delivery of ablative dose for OM lesions, especially those adjacent to historically dose-limiting organs at risk, where conventional approaches preclude ablative dosing.

Methods and materials: The RSSearch Registry was queried for OM patients (1-5 metastatic lesions) treated with SMART. Freedom from local progression (FFLP), freedom from distant progression (FFDP), progression-free survival (PFS), and overall survival (LS) were estimated using the Kaplan-Meier method. FFLP was evaluated using RECIST 1.1 criteria. Toxicity was evaluated using Common Terminology Criteria for Adverse Events version 4 criteria.

Results: Ninety-six patients with 108 OM lesions were treated on a 0.35 T MR Linac at 2 institutions between 2018 and 2020. SMART was delivered to mostly abdominal or pelvic lymph nodes (48.1%), lung (18.5%), liver and intrahepatic bile ducts (16.7%), and adrenal gland (11.1%). The median prescribed radiation therapy dose was 48.5 Gy (range, 30-60 Gy) in 5 fractions (range, 3-15). The median biologically effective dose corrected using an alpha/beta value of 10 was 100 Gy₁₀ (range, 48-180). No acute or late grade 3+ toxicities were observed with median 10 months (range, 3-25) follow-up. Estimated 1-year FFLP, FFDP, PFS, and OS were 92.3%, 41.1%, 39.3%, and 89.6%, respectively. Median FFDP and PFS were 8.9 months (95% confidence interval, 5.2-12.6 months) and 7.6 months (95% confidence interval, 4.5-10.6 months), respectively.

Conclusions: To our knowledge, this represents the largest analysis of SMART using ablative dosing for non-bone OM. A median prescribed biologically effective dose of 100 Gy₁₀ resulted in excellent early FFLP and no significant toxicity, likely facilitated by continuous intrafraction MR visualization, breath hold delivery, and online adaptive replanning. Additional prospective evaluation of dose-escalated SMART for OM is warranted.