Interventional Radiotherapy (Brachytherapy) Combined with Systemic Treatment—The Influence of RAS Gene Mutations and Combined Therapy on the Results and Toxicity of Colorectal Cancer Liver Metastases

A mutation in the <i>RAS</i> genes worsens the prognosis, regardless of the line of treatment and the systemic treatment used. The greatest benefit from brachytherapy is seen in patients in the first three lines of treatment without <i>RAS</i> mutations, treated with anti-EGFR chemotherapy in the first line and trifluridine/tipiracil in the third line. Combining brachytherapy of liver metastases with systemic treatment is safe, regardless of the systemic treatment used.