Pre-op CT Scans Appear Useful in Colon Cancer

BOSTON—Preoperative CT scans may be a cost-effective way to improve management of colon cancer patients through earlier identification of those who have liver metastases, Richard S. Swanson, MD, said at the American Society of Colon and Rectal Surgeons (ASCRS) annual meeting.

He presented a retrospective study in which a significant number of patients with potentially resectable colon cancer could have been upstaged from M0 to M1 on the basis of their CT scans. If all the scans had been done preoperatively, approximately 1 in 20 patients would have had liver metastasis detected in time for doctors to do a combined colon and liver resection.

Dr. Swanson and his co-authors at University of Massachusetts Memorial Health Care, Worcester, estimated the potential cost saving could translate to $850 per patient if all colon cancer patients had a preoperative CT scan.

In a postconference interview with ONI, Dr. Swanson, chief of surgical oncology at the hospital, stressed that the study was not conclusive, but a “what if” examination raising questions for further study. “The point of this is a hypothesis. Possibly we could save money and improve care. It needs to be tested,” he said, noting that he is trying to set up a prospective study.

The retrospective study was designed to address a controversial recommendation that a National Institutes of Health Consensus Conference published 10 years ago (JAMA 264:1444, 1990). The conference recommended that all colon cancer patients have a CT scan of the abdomen for disease staging.

The conference was criticized at the time, Dr. Swanson said, for not having enough data to make the recommendation, and many surgeons still wonder whether a preoperative CT scan is more useful than one done after surgery.

Stymied by the continuing lack of data, the Massachusetts group decided to see what the hospital’s experience had been and might have been. It reviewed 190 consecutive patients diagnosed with potentially resectable colon cancer from 1988 to 1997. Of these, it found 123 who had CT scans either before surgery or within 2 months after colon resection.

Twenty-one (17%) of the 123 patients were found to have liver metastases on their CT scans. These patients included 1 (14%) who was upstaged from stage I to stage IV, 5 (10%) upstaged from stage II to stage IV, and 15 (23%) who went from stage III to stage IV. This led the researchers to conclude that a CT scan can upstage 10% to 23% of all patients with potentially resectable colon cancers.

Six (4.9%) of the scanned patients had resectable liver metastases and thus could possibly have had a combined colon and liver resection if their CT scans had been done preoperatively.

“This is a hypothesis that needs to be tested,” Dr. Swanson said. “There could be other financial costs. Other factors might come into play that might negate the cost benefits to the patient. For example, if morbidity of doing combined surgery is significant, that might translate into complications and more postoperative care.”

The issue is important, he added, because pending more data to back up the CT scan recommendation, some surgeons do not order a CT scan for patients with early-stage colon cancer unless they see a pattern that suggests metastasis. “In the majority of cases, patients do get a CT scan now,” he said, “but it’s not an absolute.”