Doctors may be able use an advanced X-ray called a CT scan to see whether patients with advanced colorectal cancer are responding to treatment with Avastin and chemotherapy, U.S. researchers said on Tuesday.

Currently, there are no tools besides surgery to see if people with advanced colorectal cancer that has spread to the liver are responding to treatment with chemotherapy and Roche unit Genentech’s cancer drug Avastin. And many patients with this advanced form of cancer are poor candidates for surgery.

“For the patient, you would have to wait for the tumor to resurface to have a sense for whether the treatment was working,” Dr Jean-Nicolas Vauthey of the University of Texas M.D. Anderson Cancer Center said in a telephone interview.

“We had no good tool to evaluate response,” said Vauthey, whose study appears in the Journal of the American Medical Association.

He said the findings are preliminary and need to be confirmed in a much larger study, but they do suggest CT scans might help doctors offer more personalized treatment for their patients.

Vauthey, a surgeon, said most doctors rely on tumor shrinkage to see if patients are responding to treatment, but he said that is not always a good indicator of response.

In surgery patients, doctors could tell by examining changes in the size and structure of tumors whether a patient was responding to the drug combination - the standard of care for most patients with advanced colorectal cancer - and had a good chance at survival.

Working with radiology specialists, the team applied some of these same characteristics to develop screening characteristics for CT scans.

To test these, the researchers analyzed a total of 234 colorectal liver metastases from 50 patients who had their tumors removed after treatment with Avastin and chemotherapy between 2004 and 2007.

All patients had CT scans at the start and end of the treatment. Radiologists studied the images for changes in the shape and structure of the tumors. They noticed that in patients who had a good response, the tumors changed into almost cyst-like structures with well-defined borders.

And they found they could classify patients into one of three categories, with type 1 patients having a good response and the best chances of survival, and those with type 2 or type 3, having poorer or no response.

The team then analyzed data on 82 patients whose colon cancer was too advanced for surgery. In those patients whose CT scans suggested they had a good response, median survival rose to 31 months, compared with 19 months in those who had an incomplete or no response to the drug, Vauthey said.

“That is one year extra median survival. That is quite meaningful for patients who will never be cured from their disease,” he said.

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* Scans may offer better tool to test drug response

* For some, scans could replace wait-and-see approach

By Julie Steenhuysen

CHICAGO (Reuters)