Emerging Applications of Stereotactic Ablative Radiotherapy in Oligometastatic Colorectal Cancer

TL;DR

Stereotactic ablative radiotherapy (SABR) is being explored as a promising treatment for patients with limited metastatic colorectal cancer, offering improved survival and local control.

Contribution

This review highlights the emerging role of SABR in oligometastatic colorectal cancer and outlines strategies to overcome its current limitations.

Findings

SABR provides excellent local control and low toxicity for oligometastatic CRC patients.

Randomized trials like SABR-COMET show survival benefits for oligometastatic cancer, including CRC.

Technical and biological challenges remain, but new strategies like MR-guided radiotherapy and biomarkers are being explored.

Abstract

Colorectal cancer (CRC) is a major cause of cancer mortality worldwide, with metastatic disease remaining the main driver of poor prognosis. In recent years, the concept of oligometastatic disease, where patients present with a limited number of metastases, has created an opportunity to use local therapies with curative intent. Stereotactic ablative radiotherapy (SABR) has become increasingly important in this setting, as it allows the delivery of high, ablative doses with excellent local control and generally low toxicity. Notably, randomised data such as SABR-COMET, alongside large prospective series including SABR-5, have demonstrated improvements in survival outcomes in the context of oligometastatic disease across mixed primary tumour types, with CRC patients making up a relatively small proportion in these trials. This has presented SABR as a practical treatment option for patients with oligometastatic CRC, although more CRC-specific phase III trials are needed. Other challenges include the radioresistance of CRC metastases, and treatment outcomes that vary depending on the anatomical site, tumour biology, and prior therapies. Technical issues such as motion management and organ-at-risk constraints also continue to limit dose escalation. Emerging strategies—including MR-guided radiotherapy, proton-based SABR, integration with systemic agents such as immunotherapy, and the use of biomarkers and artificial intelligence to refine patient selection—are beginning to address these limitations. This review summarises the current evidence and emerging advancements to highlight how SABR may evolve as part of an integrated approach to oligometastatic CRC.

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