LAUSR

Background/Aim: Anti-EGFR antibodies or bevacizumab comprise first-line treatment for patients with RAS wild-type colorectal liver metastases (CLM). Which marker better predicts efficacy, early tumor shrinkage or morphologic response, still remains unclear. Patients and Methods: We retrospectively evaluated 155 patients with KRAS exon 2 wild-type CLM treated with bevacizumab (BEV group) or anti-EGFR antibodies (EGFR group). Three radiologists independently assessed early tumor shrinkage (ETS) and early optimal morphologic response (EOMR) from baseline and first follow-up CT scan. Results: Patients with ETS had longer progression-free survival (PFS) than those without ETS [hazard ratio (HR)=0.69] and ETS tended to be observed in the EGFR group, while patients with EOMR had longer PFS than those without EOMR (HR=0.64) and EOMR tended to be observed in the BEV group. Conclusion: Among patients with KRAS exon 2 wild-type CLM, EOMR and ETS may predict better PFS, especially in patients treated with bevacizumab and anti-EGFR antibodies, respectively.