MR-guided stereotactic radiotherapy of infra-diaphragmatic oligometastases: Evaluation of toxicity and dosimetric parameters

Mette van Overeem Felter, Pia Krause Møller, Mirjana Josipovic, Susanne Nørring Bekke, Uffe Bernchou, Eva Serup-Hansen, Kasper Madsen, Parag Parikh, Joshua Kim, Poul Geertsen, Claus P Behrens, Ivan R Vogelius, Mette Pøhl, Tine Schytte, Gitte Fredberg Persson

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

BACKGROUND AND PURPOSE: The SOFT trial is a prospective, multicenter, phase 2 trial investigating magnetic resonance (MR)-guided stereotactic ablative radiotherapy (SABR) for abdominal, soft tissue metastases in patients with oligometastatic disease (OMD) (clinicaltrials.gov ID NCT04407897). We present the primary endpoint analysis of 1-year treatment-related toxicity (TRAE).

MATERIALS AND METHODS: Patients with up to five oligometastases from non-hematological cancers were eligible for inclusion. A risk-adapted strategy prioritized fixed organs at risk (OAR) constraints over target coverage. Fractionation schemes were 45-67.5 Gy in 3-8 fractions. The primary endpoint was grade ≥ 4 TRAE within 12 months post-SABR. The association between the risk of gastrointestinal toxicity and clinical and dosimetric parameters was tested using a normal tissue complication probability model.

RESULTS: We included 121 patients with 147 oligometastatic targets, mainly located in the liver (41%), lymph nodes (35%), or adrenal glands (14%). Nearly half of all targets (48%, n = 71) were within 10 mm of a radiosensitive OAR. No grade 4 or 5 TRAEs, 3.5 % grade 3 TRAEs, and 43.7% grade 2 TRAEs were reported within the first year of follow-up. We found a significant association between grade ≥ 2 GI toxicity and the parameters GI OAR D 0.1cc, D 1cc, and D 20cc. CONCLUSION: In this phase II study of MR-guided SABR of oligometastases in the infra-diaphragmatic region, we found a low incidence of toxicity despite half of the lesions being within 10 mm of a radiosensitive OAR. GI OAR D 0.1cc, D 1cc, and D 20cc were associated with grade ≥ 2 GI toxicity.

Original languageEnglish
Article number110090
JournalRadiotherapy & Oncology
Volume192
ISSN0167-8140
DOIs
Publication statusPublished - Mar 2024

Keywords

  • MR-linac
  • Oligometastatic disease
  • Risk-adaption
  • SABR
  • SBRT
  • Stereotactic ablative radiotherapy
  • Stereotactic body radiotherapy
  • Toxicity

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