CHICAGO – Long-term intensive blood and computed tomography follow-up offered no significant advantage over minimal follow-up for detecting colorectal cancer recurrences in the phase III FACS trial.
The proportion of patients with recurrence treated surgically with curative intent was 6.7% with intensive carcinoembryonic antigen (CEA) testing, 8% with monthly computed tomography imaging and 6.6% with combination CEA plus CT, compared with 2.3% with minimal follow-up involving a single CT scan.
After adjustment, it was about three times more likely that patients would have a recurrence with CEA (adjusted odds ratio, 2.70; P = .035), monthly CT imaging (OR, 3.45; P = .007) and CEA plus CT (OR, 2.95; P = .021) than with minimal follow-up.
"This result appeared to be quite robust" and was independent of cancer stage, co-primary investigator Dr. David Mant said at the annual meeting of the American Society of Clinical Oncology.
There was virtually no deviation in protocol by patients, however, the desire for unscheduled CT scans by surgeons meant that up to 30% in the minimal follow-up arm had 1 or more additional CTs, he noted. Still, in a per protocol analysis, the absolute differences in recurrence were 3.8- to 5.4-times higher with intensive follow-up. Again, there was no evidence of an additive effect of CEA plus CT.
Guidelines in the United States and Europe stress intensive follow-up including routine history and physical examination, CEA monitoring, yearly colonoscopy and repeated CT scans in those at high risk of recurrence.
The FACS (Follow-Up After Colorectal Surgery) trial looked at whether long-term intensive follow-up was worthwhile. Though commonplace after curative surgery, economic modeling suggests intensive followup may not be cost-effective and claims of a substantial overall survival benefit are inconsistent with the reported frequency and effectiveness of treatment for recurrence, explained Dr. David Mant, emeritus professor of general practice, Oxford University.
"As a long-term family physician, I’d seen many patients being followed-up for cancer and watched their cycle of deep anxiety, followed usually by relief, but sometimes with misery, as they waited for their follow-up appointments," he added. "It seemed to me that it was a very bad idea to carry on with this practice, unless it was to their benefit."
FACS involved 1,202 patients who were disease free on colonoscopy and CT imaging and had a blood CEA level of 10 mcg/L or less (Dukes’ stages A-C) after treatment for primary colorectal cancer. Their median age was 70 years.
Patients were randomly assigned to one of four follow-up regimens: "minimal" follow-up based mainly on symptoms and a single CT scan at 12-18 months; "CEA," which included minimal follow-up, plus 3 monthly blood CEA tests for 2 years then 6 monthly tests in years 3-5; "CT," which included minimal follow-up plus intensive CT imaging involving 6 monthly scans of the chest, abdomen, and pelvis for 2 years, and then annually for another 3 years; and "CEA plus CT," which included the CEA regimen in group 2 and the CT measures in group 3.
If during monitoring, a patient’s CEA level was 7 mcg/L or more above their baseline level at trial entry, the test was repeated as soon as possible. If the second test was also above the threshold, the patient’s physician was asked to refer the patient urgently to the local hospital.
Overall, 6% of patients (71/1,202) developed a recurrence treated surgically with curative intent. There was little difference between patients according to Duke’s staging (stage A, 5.1%; stage B, 6.1%; stage C, 6.2%), reported Dr. Mant and coprincipal investigator Dr. John Primrose of University of Southhampton, U.K.
"You actually do need rigorous initial staging to detect residual disease before you embark on any follow-up," Dr. Mant stressed. "I think both John and I are convinced that the reason why we have a 6% overall recurrence rate is because the people in this trial were appropriately staged. The survival curves don’t suggest they were any less sick than patients in other trials."
At the time of the analysis, 59% of patients with a recurrence treated with curative intent were still alive, but there was no statistical difference in colorectal cancer deaths (P = .66) or total deaths (P = .45) between the minimum and intensive follow-up arms, he said.
In a meta-analysis that integrated the FACS data with that from three previous trials, the overall effect of intensive follow-up was not significant (OR, 0.96; P = .56), Dr. Mant said. The number needed to treat to detect potentially curable recurrence with intensive follow-up is about 20 to 25 and that predicts a number-needed-to-treat of about 40 to 50 for 5-year post-recurrence survival.