What if any, is your radiation approach to treating hepatic metastases abutting/invading luminal GI structures?  

In the setting of a patient with metastatic CRC (RAS mutated) progressing on first-line therapy, with infiltrative liver metastases abutting the gastric wall with threatened invasion, can you utilize RT to prevent gastric invasion/ obstruction? What would be your preferred dose and fractionation? How do you weigh the risk of fistula/perforation with these regimens if the patient is switching to second-line chemotherapy?