Using routine computed tomography ( CT ) imaging to analyze form and structural changes to colorectal liver metastasis after Bevacizumab ( Avastin ) and chemotherapy may predict overall survival.
The findings are published in the Journal of American Medical Association.

When combined with chemotherapy, the angiogenesis inhibitor Bevacizumab is associated with both improved survival in those with metastatic colorectal cancer and higher rates of pathologic response in patients undergoing surgical resection of colorectal liver metastases.

Prior to the JAMA study, Jean-Nicolas Vauthey and his MD Anderson colleagues looked at pathology in patients who had undergone resection for colorectal liver metastasis, and found those who received Bevacizumab in combination with chemotherapy achieved better pathologic response rates. Based on that pathologic finding of increased cell kill, Vauthey and colleagues then conducted a second preliminary study and uncovered that these patients were distributed in three groups - complete, major and minor response - with a strong survival correlation.

Pathologic response has proven to predict improved survival and has been proposed as a new endpoint after surgery for colorectal metastases. However, a non-invasive method of predicting such a response to chemotherapy - especially biologic agents - does not exist.
MD Anderson’s Researchers moved from pathologic criteria, which are postoperative in nature, to preoperative, radiological criteria, in evaluating a patient's response to Bevacizumab. Radiologists established a very simple imaging scheme of response. Using screening CTs to evaluate morphologic changes to the tumor, Researchers selected criteria that stratified patients into one of three types of responses - optimal, incomplete or no morphologic response.

For the retrospective study, the MD Anderson Researchers analyzed a total of 234 colorectal liver metastases from 50 surgical patients, all of whom underwent preoperative chemotherapy regimen that included Bevacizumab. Patients were treated at M. D. Anderson between 2004 and 2007; all underwent routine contrast-enhanced CTs prior to and following the neoadjuvant therapy. The median follow-up time was 18 months, with March 2008 being the last follow-up.

Blinded to pathologic results, treatment regimens and outcomes, Researchers of the Department of Diagnostic Radiology independently analyzed images for morphologic changes - from heterogenous masses with poorly-defined margins to lesions homogenous and cystic in nature with sharp borders - and then classified patients into one of the three groups.

Optimal morphologic response corresponded with survival benefit after hepatic resection: the median overall survival for surgical patients who achieved optimal, complete morphologic response was not yet met. In those who had incomplete or no response, overall survival was 25 months.

To validate the findings, the team also analyzed a cohort of 82 unresectable metastatic colon cancer patients also treated with Bevacizumab-containing chemotherapy. In this group, optimal morphological response also correlated with survival, 31 months, compared with 19 months in those that achieved incomplete or no response.

Source: University of Texas MD Anderson Cancer Center, 2009

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