Increasing the number of follow-up tests for patients with stage II or III colorectal cancer does not result in a significant rate reduction in five-year overall mortality or colorectal cancer–specific mortality, according to the results from the COLOFOL randomised clinical trial. Trial researchers in Sweden, Denmark and Uruguay reported that follow-up testing with computed tomography (CT) and carcinoembryonic antigen more frequently vs less frequently offered no benefit. The results were published in JAMA, in the paper, ‘Effect of More vs Less Frequent Follow-up Testing on Overall and Colorectal Cancer–Specific Mortality in Patients With Stage II or III Colorectal Cancer - The COLOFOL Randomized Clinical Trial’.
Although intensive follow-up of patients after curative surgery for colorectal cancer is common in clinical practice, according to the trial researchers the evidence of a survival benefit is limited. Therefore, the investigators established this randomised clinical trial to examine overall mortality, colorectal cancer–specific mortality and colorectal cancer–specific recurrence rates among patients with stage II or III colorectal cancer who were randomised after curative surgery to two alternative schedules for follow-up testing with CT and carcinoembryonic antigen.
The trial included 2,509 patients with stage II or III colorectal cancer treated at 24 centres in Sweden, Denmark and Uruguay from January 2006 through December 2010 and followed up for five years (ending December 2015). Patients were randomised either to follow-up testing with CT of the thorax and abdomen and serum carcinoembryonic antigen at six, 12, 18, 24, and 36 months after surgery (high-frequency group; n=1,253 patients) or at 12 and 36 months after surgery (low-frequency group; n= 1,256 patients).
The five-year overall patient mortality rate in the high-frequency group was 13.0% (161/1,253) vs 14.1% (174/1,256) in the low-frequency group (p=0.43), and five-year colorectal cancer–specific mortality rate in the high-frequency group was 10.6% (128/1,248) vs 11.4% (137/1250) in the low-frequency group (p=0.52). The colorectal cancer–specific recurrence rate was 21.6% (265/1,248) in the high-frequency group vs 19.4% (238/1,250) in the low-frequency group (p=0.15).
“The three extra scans don't achieve anything. Twenty percent of the patients experience relapses, and approximately 11 percent die within the first five years due to the recurrence of their cancer,” said Professor Søren Laurberg, Aarhus University Hospital, Aarhus, Denmark. “This is the case irrespective of whether they have been scanned two or five times. There is no significant difference. The money is therefore spent in vain, while the extra scans expose patients to unnecessary radiation."
In some cases, a cancer relapse was discovered earlier because of the extra scans, but this did not increase the chances of the patients surviving the first five years - this is despite all of the test subjects referred for further examination at specialist departments following the slightest suspicion that the cancer had returned.
Another important partial result is that the number of relapses - 20 percent - is modest in relation to what the researchers expected.
"All of the test subjects have been stage two and three patients with advanced cancer, so we expected that this figure would be at least the double. It's an encouraging sign that the diagnosis and treatment has been significantly improved in recent years," added Professor Laurberg.
Nevertheless, these findings should be compared to the fact that many countries have actually increased the amount of follow-up testing in the belief that more testing improves survival.
"From the beginning, we wanted to get more countries involved in the study, and we were in discussions with Norway and Ireland, amongst others. But they pulled out because they had already introduced extra scans, and it's practically impossible to find test subjects who're willing to say yes to fewer follow-ups," explained Professor Laurberg, who describes the research result as an important 'non-result' in relation to the clinical guidelines in the many countries which recommend more frequent follow-ups.
He expects that the study will lead to the recommended frequency of follow-ups being reduced, probably to the Danish level, where the follow-up for patients after colorectal cancer operations has remained at one and three years.
"As I see it, the study has in this way prevented the introduction of more frequent follow-ups after surgery for colorectal cancer on a less than stringent basis," he concluded. “But they must make a difference. In Denmark a CT scan costs DKK 2,500 (US$395), so with regard to the question of two or five scans, savings of DKK 7,500 ($ 1185) per patient can be made, without even thinking of the working hours at the hospitals and lost working hours for the people who take time off work and spend it on an unnecessary scanning.”