Research published in the Dec. 2 issue of the Journal of the American Medical Association suggests that criteria based on CT imaging of changes in tumors from colorectal liver metastases after chemotherapy with the drug bevacizumab (Avastin, Genentech/Roche) may have the potential to predict overall survival.
Yun Shin Chun, MD, and colleagues at the University of Texas M.D. Anderson Center in Houston conducted a study to validate novel tumor response criteria based on morphologic changes observed on CT in patients with colorectal liver metastases treated with bevacizumab containing chemotherapy regimens.
The researchers analyzed a total of 234 colorectal liver metastases from 50 patients who underwent hepatic resection after preoperative chemotherapy that included bevacizumab. All the 50 patients underwent routine contrast enhanced CT at the start and end of preoperative therapy.
Three radiologists evaluated the images for morphologic response, based on the criteria: metastases changing from heterogeneous masses with ill-defined margins into homogeneous hypoattenuating lesions with sharp borders. “These criteria were validated with a separate cohort of 82 patients with unresectable colorectal liver metastases treated with bevacizumab containing chemotherapy,” the authors noted.
“Morphologic criteria correlated strongly with the percentage of residual tumor cells and also with pathologic response stratified as complete, major, or minor using 50 percent residual tumor cells as the cutoff value between major and minor pathologic response," Chun and colleagues wrote. "Optimal morphologic response to preoperative therapy translated into a survival benefit after hepatic resection.”
Among patients who underwent hepatic resection, median overall survival was 25 months with incomplete or no morphologic response. In the validation cohort, patients with optimal morphologic response had median overall survival of 31 months compared with 19 months with incomplete or no morphologic response, according to the researchers.
“Among patients with colorectal liver metastases treated with bevacizumab containing chemotherapy, CT-based morphologic criteria had a statistically significant association with pathologic response and overall survival," the researchers concluded.