Background: Histological response of colorectal cancer liver metastases to chemotherapy may be graded based on the extent of tumor regression. The knowledge about the effect of bevacizumab, if given in addition to fluoropyrimidines and oxaliplatin, on tumor regression and its consequences on clinical outcome is limited.
Materials and methods: Resected liver metastases from patients of 2 prospective nonrandomized trials (fluoropyrimidines and oxaliplatin +/- bevacizumab) were analyzed retrospectively. Histological response was analyzed according to an established tumor regression grading for colorectal cancer liver metastases. Tumor regression grades (TRGs) were correlated to progression-free and overall survival.
Results: Bevacizumab improved tumor regression to chemotherapy significantly. Improvement in histological response was translated into a significant prolongation of progression-free and overall survival.
Conclusions: Classifying histological response based on tumor regression grades qualifies to predict the outcome of patients with colorectal cancer liver metastases. Tumor regression grading provides a standardized pathological response evaluation, against which radiologic response on chemotherapy including biologicals can be prospectively evaluated.