Widening the therapeutic window for central and ultra-central thoracic oligometastatic disease with stereotactic MR-guided adaptive radiation therapy (SMART)

Grace Lee; Zhaohui Han; Elizabeth Huynh; Michael C Tjong; Daniel N Cagney; Mai Anh Huynh; Benjamin H Kann; David Kozono; Jonathan E Leeman; Lisa Singer; Christopher L Williams; Raymond H Mak

doi:10.1016/j.radonc.2023.110034

Widening the therapeutic window for central and ultra-central thoracic oligometastatic disease with stereotactic MR-guided adaptive radiation therapy (SMART)

Radiother Oncol. 2024 Jan:190:110034. doi: 10.1016/j.radonc.2023.110034. Epub 2023 Nov 27.

Authors

Affiliations

¹ Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
² Department of Radiation Oncology, London Regional Cancer Program, London, ON, Canada.
³ Radiotherapy Department, Mater Private Network, Dublin, Ireland.
⁴ Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA.
⁵ Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA. Electronic address: rmak@partners.org.

PMID: 38030080
DOI: 10.1016/j.radonc.2023.110034

Abstract

Background/purpose: Central/ultra-central thoracic tumors are challenging to treat with stereotactic radiotherapy due potential high-grade toxicity. Stereotactic MR-guided adaptive radiation therapy (SMART) may improve the therapeutic window through motion control with breath-hold gating and real-time MR-imaging as well as the option for daily online adaptive replanning to account for changes in target and/or organ-at-risk (OAR) location.

Materials/methods: 26 central (19 ultra-central) thoracic oligoprogressive/oligometastatic tumors treated with isotoxic (OAR constraints-driven) 5-fraction SMART (median 50 Gy, range 35-60) between 10/2019-10/2022 were reviewed. Central tumor was defined as tumor within or touching 2 cm around proximal tracheobronchial tree (PBT) or adjacent to mediastinal/pericardial pleura. Ultra-central was defined as tumor abutting the PBT, esophagus, or great vessel. Hard OAR constraints observed were ≤ 0.03 cc for PBT V40, great vessel V52.5, and esophagus V35. Local failure was defined as tumor progression/recurrence within the planning target volume.

Results: Tumor abutted the PBT in 31 %, esophagus in 31 %, great vessel in 65 %, and heart in 42 % of cases. 96 % of fractions were treated with reoptimized plan, necessary to meet OAR constraints (80 %) and/or target coverage (20 %). Median follow-up was 19 months (27 months among surviving patients). Local control (LC) was 96 % at 1-year and 90 % at 2-years (total 2/26 local failure). 23 % had G2 acute toxicities (esophagitis, dysphagia, anorexia, nausea) and one (4 %) had G3 acute radiation dermatitis. There were no G4-5 acute toxicities. There was no symptomatic pneumonitis and no G2 + late toxicities.

Conclusion: Isotoxic 5-fraction SMART resulted in high rates of LC and minimal toxicity. This approach may widen the therapeutic window for high-risk oligoprogressive/oligometastatic thoracic tumors.

Keywords: Adaptive radiotherapy; Central; Isotoxic; Local control; Oligometastasis; Oligoprogressive; Stereotactic Body Radiotherapy; Thoracic; Toxicity; Ultracentral.

MeSH terms

Humans
Lung Neoplasms* / diagnostic imaging
Lung Neoplasms* / pathology
Lung Neoplasms* / radiotherapy
Magnetic Resonance Imaging / methods
Neoplasm Recurrence, Local
Radiation Injuries*
Radiosurgery* / methods
Radiotherapy Planning, Computer-Assisted / methods
Thoracic Neoplasms* / radiotherapy