Those over 50 have surely received the letter inviting them to participate in colon cancer screening to rule out early symptoms of this disease. These tests consist of a self-sample, which can be done at home, to analyze the possible presence of blood in the stool hidden from plain sight. Until now, if blood was discovered in the stool, a colonoscopy, a test that consists of exploring the inside of the intestine, was performed to confirm if this blood was caused by the presence of cancerous cells in the colon.
However, a study by Hospital Clínic de Barcelona-IDIBAPS and Hospital Universitario de Canarias has confirmed that the fecal occult blood test, a much less invasive test, is just as effective as colonoscopy in detecting the presence of this disease. The Colonprev study, which has been published in The Lancet, is the first international study of this dimension, as 57,000 people have been followed for ten years to compare the effectiveness of the two main strategies.
In total, men and women between 50 and 69 years old from eight autonomous communities participated, including Catalonia, but also Aragon, Canary Islands, Galicia, Madrid, Murcia, Basque Country, and the Valencian Community. Participants were divided into two groups: half of the patients were called to undergo a colonoscopy every two years, and the other half to perform the fecal immunochemical test, to study colorectal cancer mortality after a decade. The project has been funded by the Spanish Association Against Cancer (AECC) and the Carlos III Health Institute.
"The conclusion is that a less invasive test such as the fecal occult blood test achieves the same results in terms of reducing mortality and reducing new cases of cancer as colonoscopy," said Dr. Antoni Castells, medical director of the Clínic and head of the Gastrointestinal and Pancreatic Oncology group at the August Pi i Sunyer Biomedical Research Institute (IDIBAPS).
Mortality from colorectal cancer after ten years was similar in both groups: 0.22% in the colonoscopy group and 0.24% in the fecal occult blood test group, as was the incidence of tumors. "With these results, the two strategies are equivalent," emphasized Dr. Castells. A test that is not only less invasive but also more economical and accessible to the population.
With these results, researchers hope that participation in screening for early detection of colon and rectal cancer, which has been carried out in Catalonia for years, will increase. Screening not only allows detecting cancer in early stages of the disease, but can even prevent it because it allows observing premalignant lesions, known as adenomas, and removing them before they evolve into cancer. A disease that already represents the second most deadly type of cancer and the most detected malignant tumor in all of Spain.
In fact, the Colonprev project has also shown that people are more predisposed to participate in a stool test than in a colonoscopy, as 40% of people invited to take a stool test decided to be part of the study, while only 32% of the group directly called to undergo a colonoscopy decided to join.
A previous article from the same project, but focused on the results obtained in the first round of the screening program and published in The New England Journal of Medicine, already showed in 2012 that the two strategies detected the same number of tumors, but this new work goes further and manages to show that these two techniques are also equivalent in terms of reducing mortality from colorectal cancer.
Extending the age for screenings
"We believe that this study can incentivize participation in screenings, seeing that it is an easy, comfortable test to perform and that 95% of people who participate in the program save themselves a colonoscopy," remarked Castells. Between 1% and 5% of cases detect blood, and furthermore, a positive result is not always synonymous with cancer, since in most cases blood can be caused by benign polyps or other lesions in the digestive system.
In Catalonia, 50% of the population undergoes the screening test, while the European objective would be to reach at least 65%. "Participation is a key issue and we believe we have to make efforts to improve it and we have to address it in many ways," defended Castells, who has claimed the need to make efforts to target these specific population groups.
The researchers have also asked to extend the age range of people to whom the screening is directed, since it is currently aimed at men and women between 50 and 69 years old, while doctors have advocated extending this age up to 74 years.
Currently, there is also a debate about whether to advance these tests to 45 years, because an increase in cases has been observed in this age group. Even so, Dr. Enrique Quintero, gastroenterologist at the Hospital Universitario de Canarias and coordinator of the study, has pointed out that it is necessary to prioritize the extension to 74 years and improve participation in all autonomous communities. "We cannot move to screening below 50 years if in some regions 40% participation is not reached in the medium-risk population."