CT Changes in Colorectal Liver Metastases Predict Survival
By Zosia Chustecka
Medscape Medical News
December 2, 2009 — In patients with colorectal liver metastases who were treated with bevacizumab (Avastin) in combination with chemotherapy, computed tomography (CT) scans showed changes in the metastases that predicted survival.
The changes that showed up on the CT scans are described as "novel" by researchers writing in the December?2 issue of the Journal of the American Medical Association.
They describe how the metastases changed from "heterogeneous masses with ill-defined margins into homogeneously hypoattenuating lesions with sharp borders,?.?.?. which in some cases could mimic a cyst." These changes, on responding to treatment, "likely reflect the replacement of treated tumor by fibroconnective tissue rather than tumor necrosis," the researchers add.
Patients with an "optimal morphologic response" to preoperative therapy on the CT scans showed improved overall survival. The association between the CT changes and overall survival was statistically significant, the team reports.
In contrast, there was no correlation between survival and assessment by the traditional size-based radiological criteria, the Response Evaluation Criteria in Solid Tumors (RECIST), which were designed to assess tumor volume reduction after cytotoxic chemotherapy.
"Patients with an optimal morphology response can be reassured that they are benefiting from treatment, even if the tumor isn't shrinking by standard size criteria," said corresponding author Jean Nicholas Vauthey, MD, from the Department of Surgical Oncology at the University of Texas M.D. Anderson Cancer Centre in Houston. "For patients with a cancer that is responding to therapy, there are more options for subsequently using less intense therapies that improve the patients' quality of life," he told Medscape Oncology.
Retrospective Study
The results come from a retrospective study that analyzed 234 colorectal liver metastases from 50 patients who underwent hepatic resection and who had received preoperative treatment with bevacizumab and chemotherapy. All patients underwent routine CT scanning at the start and end of the preoperative treatment.
In addition, the researchers analyzed CT scans for a separate validation cohort of 82 patients with unresectable colorectal liver metastases treated with bevacizumab-containing chemotherapy.
Patients in both cohorts who showed an optimal morphologic response to preoperative therapy on the CT scans had improved overall survival.
Among the patients who underwent hepatic resection, median overall survival was not reached in those who showed an optimal morphologic response; the median overall survival was 25 months for patients who had no or an incomplete morphological response (P?= .03). In the nonsurgical validation cohort, the median overall survival was 31 months in patients with an optimal morphological response and 19 months in those who had no or an incomplete morphological response (P?= .009).
In addition, the morphological response assessed on CT scans correlated with pathologic response, stratified as complete, major, or minor response. Again, the RECIST criteria did not correlate with pathologic response.
"Thus, our results indicate that morphological response may be a useful, noninvasive surrogate marker of pathological response and improved survival in patients with colorectal metastases receiving a bevacizumab-containing regimen," the authors conclude.
Dr. Vauthey explained that bevacizumab is used in about 80% of patients as part of their initial therapy for metastatic disease. The morphological changes in the metastases seen on the CT scan are "more pronounced" after treatment with chemotherapy that includes bevacizumab, he said, adding that, "in our experience, this response pattern is less common" in patients treated with other biological agents.
Dr. Vauthey reports receiving grants and honoraria from Sanofi-Aventis, Genentech, and Roche. Several coauthors have disclosed relevant financial relationships, as listed in the paper.
