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Colon cancer screening: Detect early cancer
Colon cancer is the third most common cancer in men and the second most common in women worldwide. The chances of recovery depend heavily on how early the disease is diagnosed. An international group of experts has now published a comprehensive assessment of colorectal cancer screening procedures. According to this, stool tests and endoscopic examinations can significantly reduce colon cancer mortality.
Colon cancer accounts for ten percent of all new cancers
According to the German Cancer Research Center (DKFZ), colorectal cancer accounts for around ten percent of all new cancer cases worldwide. As the countries' incomes rise, the number of new cases of colorectal cancer increases. The situation is different with survival rates: about 60 percent of those affected in the wealthy industrialized nations survive the first five years after a colon cancer diagnosis; in the poor part of the world, the maximum is 30 percent of those affected. Early diagnosis would be important. Because early detection can save lives. But which cancer test is the safest? Experts report that stool tests as well as endoscopic procedures such as colonoscopy can lower mortality from colon cancer.
Detect disease at an early stage
A number of screening procedures are designed to detect colorectal cancer at an early stage, thereby reducing cancer mortality and the rate of new cases. But for which of the processes has this been sufficiently scientifically proven?
On behalf of the cancer research agency IARC of the World Health Organization (WHO), an international group of experts has now examined the studies published on the various screening methods.
Michael Hoffmeister from the German Cancer Research Center (DKFZ) was also involved in the evaluation, which was published in the specialist journal “New England Journal of Medicine”.
Reduce colorectal cancer mortality
The IARC experts gave the ratings "sufficiently proven" or "limitedly demonstrated" that a procedure actually reduces the rate of new cases or the mortality rate - or they found insufficient or no evidence.
The researchers classified the two stool-based tests (immunological tests and the guaiac enzyme test) as sufficient to reduce colon cancer mortality - provided that they are carried out regularly every two years.
The IARC experts rated the evidence that just one examination with one of the endoscopic procedures reduced mortality as equally proven:
This includes the so-called “small colonoscopy” (sigmoidoscopy), which only covers the last part of the colon, and colonoscopy, in which the entire colon is inspected.
Endoscopic procedures and stool tests
However, according to the IARC researchers, the reduction in the incidence of colorectal cancer has so far only been sufficiently proven for the two endoscopic procedures.
There are results from large randomized studies for sigmoidoscopy and numerous results from observational studies for colonoscopy.
“The results of four large randomized studies are still pending for colonoscopy. Nevertheless, in the opinion of most experts, a risk reduction for new illnesses has been adequately proven, since a colonoscopy contains a sigmoidoscopy and one can assume an even greater effectiveness when mirroring the entire intestine, ”says Hoffmeister.
"For the immunological stool test, on the other hand, the studies regarding the reduction in the incidence rate are not yet sufficient. However, there are indications that the immunological stool tests, if they are carried out regularly every two years, can detect as many precursors and carcinomas in the intestine as a single colonoscopy. "
Computer tomography screening was not convincing
The benefits outweighed the risks of the examination in both endoscopic procedures and stool tests.
The IARC experts, however, were not able to convince the previous study situation on screening the colon with a computed tomography.
With its assessments, the IARC takes an international perspective: "Not every country has the resources to offer all people an extensive examination such as colonoscopy as part of the screening," explains Hoffmeister.
"It is therefore important to be able to recommend effective, cost-effective procedures that are adapted to the performance of the respective health system." (Ad)