Systematic Reviews
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Feb 21, 2022; 28(7): 745-754
Published online Feb 21, 2022. doi: 10.3748/wjg.v28.i7.745
Stereotactic radiotherapy and the potential role of magnetic resonance-guided adaptive techniques for pancreatic cancer
Tai Ermongkonchai, Richard Khor, Vijayaragavan Muralidharan, Niall Tebbutt, Kelvin Lim, Numan Kutaiba, Sweet Ping Ng
Tai Ermongkonchai, Richard Khor, Sweet Ping Ng, Department of Radiation Oncology, Olivia Newton-John Cancer Centre at Austin Health, Heidelberg 3084, Victoria, Australia
Vijayaragavan Muralidharan, Department of Surgery, Austin Health, Heidelberg 3084, Victoria, Australia
Niall Tebbutt, Department of Medical Oncology, Olivia Newton-John Cancer Centre at Austin Health, Heidelberg 3084, Victoria, Australia
Kelvin Lim, Numan Kutaiba, Department of Diagnostic Radiology, Austin Health, Heidelberg 3084, Victoria, Australia
Author contributions: Ermongkonchai T performed the literature search and wrote the manuscript; Khor R, Muralidharan V, Tebbutt N, Lim K, Kutaiba N and Ng SP performed editing and contributed to the quality of the manuscript.
Conflict-of-interest statement: No conflict-of-interest to be declared by authors of this article.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 Checklist, and the manuscript was prepared and revised according to the PRISMA 2009 Checklist.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Sweet Ping Ng, MBBS, PhD, Associate Professor, Department of Radiation Oncology, Olivia Newton-John Cancer Centre at Austin Health, 145 Studley Road, Heidelberg 3084, Victoria, Australia.
Received: September 13, 2021
Peer-review started: September 13, 2021
First decision: October 16, 2021
Revised: November 11, 2021
Accepted: January 22, 2022
Article in press: January 22, 2022
Published online: February 21, 2022
Research background

Pancreatic cancer is associated with significant mortality, and unresectable tumours are commonly treated with chemoradiotherapy regimens. Conventional radiotherapy (RT) techniques have minimal impact on survival and often cause considerable toxicities. Stereotactic body radiotherapy (SBRT) is an advanced radiotherapy technique that delivers highly ablative doses in several fractions, with a steep dose fall-off outside target volumes.

Research motivation

Previous studies have supported the benefit of radiotherapy in multi-modal management of unresectable pancreatic cancers. However, there is no consensus of which RT technique yields the best survival outcomes. There is also a need for research to explore onboard imaging such as magnetic resonance-guided radiotherapy (MRgRT), which will enable treatment plans to be optimised according to intra-treatment tissue changes.

Research objectives

We aim to collate the latest data on SBRT and evaluate its survival outcomes and toxicity profiles, with comparison to conventional RT techniques. Our review will also cover the safety and efficacy of MRgRT.

Research methods

Searches were conducted on PubMed and Ovid (Medline), resulting in 1229 records. After multiple rounds of screening, 36 texts were chosen to synthesise the discussion. Records were included if they studied SBRT or MRgRT in unresectable cancers, and excluded if they involved metastatic disease, resectable tumours or used chemoradiotherapy as adjuvant to surgery.

Research results

SBRT is associated with improved survival outcomes and toxicity profiles compared to conventional RT techniques. A small proportion of unresectable patients were able to undergo surgical resection after their SBRT course. Conversion to resectability was associated with higher doses. However, dose escalation in SBRT is limited by the onboard computed tomography (CT) imaging due to its poor soft-tissue contrast. MRgRT may address these issues as magnetic resonance imaging (MRI) provides excellent tissue visualisation and is appropriate for real-time scanning. Early data indicates MRgRT as a safe and efficacious technique.

Research conclusions

SBRT may lead to improved survival outcomes and safer toxicity profiles compared to conventional RT, but is ultimately limited by onboard CT imaging. The addition of MRI-guided techniques allows the potential for dose escalation, which may be the key to achieving surgical resectability and possibly increasing the chances of cure.

Research perspectives

There is a need for large prospective trials to definitively conclude if SBRT is superior to other RT techniques. Large studies are also required to validate the safety, feasibility and efficacy of MRgRT with comparison to other RT techniques.