Clinical Outcomes after MRI Guided Stereotactic Body Radiotherapy for (Peri-) Pancreatic Tumors

Abstract

<h3>Purpose/Objective(s)</h3> Radiotherapy treatment of pancreatic cancer can be challenging due to close relationship between the tumor and radiosensitive intestines and poor visibility of the upper abdomen with conventional treatment methods. In recent years, with the introduction of MR-guided radiotherapy (MRgRT) it became possible to deliver ablative doses to (peri-)pancreatic tumors. In this multicenter cohort study, we report clinical outcomes from our first cohort of patients with (peri-)pancreatic tumors with MR-guided stereotactic radiotherapy on a 1.5 T MR-Linac. <h3>Materials/Methods</h3> All patients with (peri-)pancreatic tumors treated on the 1.5 T Unity MR-Linac between April 2019 and January 2022 at two institutes. Symptoms were reported using clinician-reported outcome measurements defined by the Common Terminology Criteria for Adverse Events (CTCAE) version 5. Quality of life (QoL) was assessed with the EORTC QLQ-C30 questionnaire and evaluated with the Global Health status. Symptoms and QoL were assessed at baseline, and at three, six and twelve months after treatment. The Kaplan-Meier analysis was performed for the 6 months-, and 1-year survival. <h3>Results</h3> The baseline characteristics of 79 patients are summarized in Table 1. The most frequently delivered SBRT scheme was 40 Gy in 5 fractions of 8 Gy. Most frequently reported grade 3 symptoms at baseline, three months follow-up, six months, and twelve months were abdominal pain (0%, 13%, 3%, and 5%); anorexia (0%, 9%, 0%, and 0%); fatigue (0%, 5%, 6%, and 5%); nausea (0%, 5%, 0%, and 5%), and diarrhea (0%, 5%, 6%, and 5%). Other grade 3 toxicity at three months follow up occurred in 5% for malabsorption; 2% of patients for vomiting; 2% for gastroparesis; 2% for weight loss; 2% for portal hypertension and 2% for gallbladder obstruction. No treatment-related toxicities higher than grade 3 were observed in our cohort. The EORTC Global Health status was 71 at baseline (n=37), 70 after three months follow up (n=20), 65 after six months (n=12), and 67 after twelve months (n=6). From the treatment start with MRgRT, the cumulative 6 months- and 1-year survival was 88%, and 74%, respectively. <h3>Conclusion</h3> In this international prospective cohort of patients with (peri-)pancreatic tumors, we observed a low incidence of major treatment-related toxicity and a stable Global Health status at three months post MRgRT on a 1.5T MR-Linac.