ESTRO 2023

Session Item

Upper GI

Session Code: 6010

Session Type: Poster (Digital)

Track: Clinical

Real-World Data of Pancreatic Cancer Treated with Ablative Radiation on a 1.5 tesla MR Linac

Rana Bahij, Denmark

Presentation Number: PO-1370

Abstract

Abstract Title:

Real-World Data of Pancreatic Cancer Treated with Ablative Radiation on a 1.5 tesla MR Linac

Authors:

Rana Bahij¹, Mathilde Ejlsmark², Tine Schytte³, Olfred Hansen⁴, Uffe Bernchou⁵, Carsten Brink⁵, Anders Bertelsen⁶, Søren Agergaard⁶, Helle Jensen⁷, Faisal Mahmood⁵, Per Pfeiffer⁴

¹Odense University Hospital, Department of Oncology, Odense , Denmark; ²Department of Clinical Research, University of Southern Denmark, Department of Oncology, Odense University Hospital, Odense , Denmark; ³Department of Clinical Research, University of Southern Denmark, Department of Oncology, Odense University Hospital, Odense , Denmark; ⁴ Department of Clinical Research, University of Southern Denmark, Department of Oncology, Odense University Hospital, Odense , Denmark; ⁵Department of Clinical Research, University of Southern Denmark, Laboratory of Radiation Physics, Odense University Hospital, Odense , Denmark; ⁶Laboratory of Radiation Physics, Odense University Hospital , Department of Oncology Odense University Hospital , Odense , Denmark; ⁷Odense University Hospital, Department of Oncology , Odense, Denmark

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Purpose or Objective

Stereotactic ablative radiotherapy has emerged as a promising new treatment modality for patients with pancreatic cancer (PC). With the introduction of online adaptive MR-guided radiotherapy (MRgRT), the treatment has evolved dramatically. It is now possible to define the organs at risk (OAR) and adapt the radiotherapy plan daily based on the anatomy of the day.

In this study, we want to investigate the feasibility, efficacy, safety, and overall survival of patients with pancreatic cancer treated with ablative radiation on a 1.5 T MR linac.

Material and Methods

The study includes all 52 patients with biopsy-proven PC treated at Odense University Hospital between Aug 2018 and Sept 2022 on a 1.5 T MR Linac. Twenty-five patients were included in the prospective Danish phase II study SBRT-PC-01 (NCT03648632) and 27 patients were included prospectively in The Multiple Outcome Evaluation of Radiation Therapy Using the MR-Linac (MOMENTUM) study (NCT04075305). The prescribed GTV dose was 50 Gy in 5 fx (n=49) or 60 Gy in 8 fx (n=3), with dose constraints to adjacent organs at risk as the limiting factor. Endpoints were adverse events (baseline, 1, 3, 6, 9, and 12 months after RT), and overall survival (OS).

Results

Of the 52 included patients, 43 were locally advanced, six were locally recurrent, and three were metastatic. The majority of the patients had induction chemotherapy (FOLFIRINOX, Gemcitabine and Nab-paclitaxel, or Gemcitabine and Teysuno (S1)). The median age was 69 years (range 40-85). Fifty participants completed the prescribed radiation treatment. The treatment of the remaining two patients was discontinued after two fractions due to biliary obstruction. Hence, the incompletion of the treatment course was not related to radiation induced adverse events. The median follow-up time from diagnosis and inclusion was 29.5 and 19.8 months, respectively. OS data is presented in the figure. The median OS from diagnosis and inclusion in the study was 27.8 (95% CI 20.8-not reached) and 15.3 months (95% CI 10.2-not reached). Overall, the treatment was well tolerated with no grade ≥ 3 toxicity observed. Nausea and abdominal pain were the main observed adverse events.

Conclusion

Online adaptive MRgRT using ablative doses for patients with PC is well tolerated and feasible. It shows promising results regarding survival and efficacy. A prospective trial on this subject is currently being planned.