The addition of stereotactic body radiation therapy (SBRT) to metastases in a limited unresectable metastatic setting might improve progression-free survival (PFS). The success of the addition of local treatments in mCRC patients depends largely on: control of microscopic disease, diagnostic accuracy of macroscopic disease and effective treatment of all detected metastases with limited additional toxicity to surrounding tissues. Until shortly, the use of SBRT was possible to a limited number of locations due to target movement or toxicity to surrounding radiosensitive structures. With the introduction of MRI-guided radiotherapy these limitations have been largely reduced due to the possibility to make a daily new treatment plan based on MRI-visualized anatomy. This allows the use of smaller margins for uncertainty with less healthy tissues in the radiation field. Thereby, a broader application of SBRT to add local control to metastases became possible.~This study is an open-label, multicenter, randomized phase II screening trial assessing the impact of SBRT in combination with systemic therapy compared to systemic therapy alone on safety and efficacy in patients with mCRC and ≤10 metastases with no option of local treatment with curative intent and with stable disease or partial response after treatment of CAPOX-B, FOLFOX-B or FOLFOXIRI-B.
A small number of colorectal cancer patients with limited oligometastases may be candidates for local treatment of metastases (e.g., resection, ablation). However, it is unclear if patients with more extensive metastatic disease benefit from local therapies to control visible metastasis.~The purpose of this study is to assess the impact of stereotactic body radiation therapy (SBRT) in combination with systemic therapy compared to systemic therapy alone on safety and efficacy in patients with metastatic colorectal cancer (mCRC) and ≤10 metastases.