CT Scan May Predict Colon Cancer Survival
TUESDAY Dec. 1, 2009 -- A CT scan of liver tumors caused by the spread of colorectal cancer may help predict overall survival after chemotherapy, researchers report.
Adding bevacizumab (Avastin) to cytotoxic chemotherapy has been shown to improve survival in patients with late-stage colorectal cancer and to produce better results in patients having surgery to remove colorectal cancer from the liver, the researchers said. But how this treatment relates to survival has not been known.
"Liver colorectal metastasis responding to the combination of bevacizumab and cytotoxic chemotherapy undergo unique morphologic changes, which can be easily recognized on routine enhanced computed tomography," said lead researcher Dr. Evelyne M. Loyer, from the University of Texas M.D. Anderson Cancer Center's Department of Diagnostic Radiology.
"Based on this observation, we developed a simple qualitative three-point scale to score the extent of the morphologic changes induced by the treatment," she said. "The scoring system we developed provides a noninvasive, simple tool to assess response to bevacizumab-containing chemotherapy in patients with colorectal metastasis."
The report is published in the Dec. 2 issue of the Journal of the American Medical Association.
To see if CT scans could predict survival in these patients, Loyer's team studied 234 colorectal liver tumors from 50 patients. All of the patients had undergone liver surgery after chemotherapy with bevacizumab.
The researchers found that survival was directly related to the amount of residual tumor cells left in the liver after chemotherapy. Based on the percentage of tumor cells left in the liver, the researchers could estimate overall survival. They confirmed their results in patients whose livers could not be operated on.
In essence, the better the response to chemotherapy, the better was the patient's survival. "Non-surgical patients with an optimal score on CT had a median survival of 31 months, while those who did not, had a median survival of 19 months," Loyer said.
"Radiographic response to bevacizumab-containing chemotherapy should not be limited to record of change in tumor size, but include a qualitative assessment of the morphology of the metastasis," she said.
"Finding a way to predict who is going to benefit from surgical liver resection is an important issue," said Dr. Durado Brooks, director of colorectal cancer at the American Cancer Society.
"If you are talking about patients already debilitated by cancer, putting them through a strenuous surgery, you would like to know that you are providing them benefit as opposed to simply exposing them to the potential harms of surgery with very limited potential for benefit," he added.
Brooks thinks before this way of predicting survival can be used widely, it will have to be tried on many more patients.
"If this can be substantiated by other investigators in other settings then it may prove beneficial, particularly helping people avoid going through surgery that's not likely to do them any good," he said.
For more on colorectal cancer, go to the U.S. National Library of Medicine.
Posted: December 2009