Pathologic Response to Bevacizumab-containing Chemotherapy in Patients with Colorectal Liver Metastases and Its Correlation with Survival

For patients with colorectal liver metastases (CLM), hepatic resection currently offers the best chance for long-term survival. Preoperative chemotherapy is now integral to the management of these patients, conferring a disease-free survival advantage over surgery alone in patients with 'upfront' resectable disease and enabling some initially unresectable CLM to become resectable. However, although surgery may improve long-term survival, up to 65.0% of patients will experience disease recurrence at 5 years and reliable prognostic factors are needed to predict those patients who are more likely to experience recurrence after resection. Recently, pathologic tumor response, defined as the 'objective measurement of residual cancer cells in resected tissue,' has been identified as a reliable prognostic factor in patients with colorectal cancer (CRC) receiving preoperative chemotherapy and has been shown to correlate with improved survival after resection of CLM. Addition of the targeted biologic agent bevacizumab to preoperative chemotherapy is associated with an increase in pathologic response rate and an increase in survival compared with chemotherapy alone in patients undergoing hepatic resection. This review discusses the data in support of pathologic response rate as an important new outcome endpoint after hepatic resection of CLM and considers the evidence to date on pathologic response to bevacizumab-containing chemotherapy in metastatic CRC and its correlation with survival.