Secondary technical resectability of colorectal cancer liver metastases after chemotherapy with or without selective internal radiotherapy in the randomized SIRFLOX trial

BACKGROUND: Secondary resection of initially unresectable colorectal cancer liver metastases (CRLM) can prolong survival. The added value of selective internal radiotherapy (SIRT) to downsize lesions for resection is not known. This study evaluated the change in technical resectability of CRLM with the addition of SIRT to FOLFOX‐based chemotherapy. METHODS: Baseline and follow‐up hepatic imaging of patients who received modified FOLFOX (mFOLFOX6: fluorouracil, leucovorin, oxaliplatin) chemotherapy with or without bevacizumab (control arm) versus mFOLFOX6 (with or without bevacizumab) plus SIRT using yttrium‐90 resin microspheres (SIRT arm) in the phase III SIRFLOX trial were reviewed by three or five (of 14) expert hepatopancreatobiliary surgeons for resectability. Reviewers were blinded to one another, treatment assignment, extrahepatic disease status, and information on clinical and scanning time points. Technical resectability was defined as at least 60 per cent of reviewers (3 of 5, or 2 of 3) assessing a patient's liver metastases as surgically removable. RESULTS: Some 472 patients were evaluable (SIRT, 244; control, 228). There was no significant baseline difference in the proportion of technically resectable liver metastases between SIRT (29, 11·9 per cent) and control (25, 11·0 per cent) arms (P = 0·775). At follow‐up, significantly more patients in both arms were deemed technically resectable compared with baseline: 159 of 472 (33·7 per cent) versus 54 of 472 (11·4 per cent) respectively (P = 0·001). More patients were resectable in the SIRT than in the control arm: 93 of 244 (38·1 per cent) versus 66 of 228 (28·9 per cent) respectively (P < 0·001). CONCLUSION: Adding SIRT to chemotherapy may improve the resectability of unresectable CRLM.