Logically, it would seem that more follow-up testing of cancer patients must be better than less - but this is not the case for patients who undergo surgery for colorectal cancer.

This is an important conclusion from a study where 2,509 patients with colorectal cancer were offered two and five follow-up tests in the form of CT scans combined with a blood test spread over the first three years after the operation.

The results have just been published in the scientific journal JAMA.

In some cases, the extra scans meant that a cancer relapse was discovered earlier, but this did not increase the chances of the patients surviving the first five years.

And this is despite the fact that all of the test subjects were referred for further examination at specialist departments following the slightest suspicion that the cancer had returned.

The futile extra scans 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.

"The three extra scans don't achieve anything. Twenty per cent of the patients experience relapses, and approximately eleven per cent die within the first five years due to the recurrence of their cancer. 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," says Clinical Professor, DMSc Søren Laurberg.

Another important partial result is that the number of relapses - the above-mentioned twenty per cent - is modest in relation to what the researchers expected.

"All of the test subjects have been stage 2 and 3 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," says Søren Laurberg, who works at the Department of Clinical Medicine at Aarhus University and at the section for colorectal and mamma-endocrine surgery in the Department of Surgery at Aarhus University hospital.

The project was launched in January 2006 on the initiative of Peer Wille-Jørgensen, who is a consultant at Bispebjerg Hospital.

His wish was to verify a number of smaller and therefore uncertain studies which indicated that it was possible to improve survival rates after surgery for colorectal cancer through more frequent follow-ups.

With this in mind, Peer Wille-Jørgensen formed a steering committee of leading Danish, Swedish and English surgeons who together designed and planned the research project, which they named COLOFOL.

The committee included Clinical Professor Søren Laurberg and Professor Henrik Toft Sørensen from the Department of Clinical Epidemiology.

They were responsible for the data analysis.

In the trial, half of the patients were offered two follow-ups after drawing lots, while the control group comprising the other half were also offered the three extra CT scans.

An important element was the preparation of fixed guidelines for which examinations should be carried out if it was suspected that the cancer had returned in one of the test subjects.

The clinical randomised study ran from 2006 until December 2010 with a concluding five-year follow-up at the end of 2015.

Since then, two-and-a-half years have been spent on analysing results from across the participating countries.

"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," explains Søren 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," says Søren Laurberg, who points out that there is a tendency towards ever more follow-ups and diagnostic imaging - also for other forms of cancer.

"But they must make a difference. In Denmark a CT scan costs DKK 2,500 (US dollar 395), so with regard to the question of two or five scans, savings of DKK 7,500 (US dollar 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," says Søren Laurberg.

The study is an unblinded clinical randomised study.

Source: Aarhus University