Colorectal cancer is one of the tumours with the highest rate of incidence and is the second cause of death from cancer in developed countries. In Spain it is the second deadliest tumour after lung cancer: in 2022, 11,142 people died from this tumour (4.2% of all deaths), and in the Basque Country more than 700 people succumbed. This cancer develops from polyps that may evolve into malignant tumours if they are not detected and removed in time.

Early detection is crucial to preventing the disease or diagnosing it in the early stages when treatment is more effective and the chances of a cure are higher. Right now, there are two main screening strategies: the faecal occult blood test, which detects microscopic traces of blood indicative of precancerous lesions or tumours; and colonoscopy, which is regarded as the most accurate test for early detection and allows the colon to be explored directly and any polyps removed before they turn into cancer, but at the same time it has more complications.

Luis Bujanda, a professor at the University of the Basque Country (UPV/EHU) and researcher at the IIS Biogipuzkoa (Health Research Institute), participated together with Jesús M. Banales (researcher in the Area of Liver and Gastrointestinal Diseases at the IIS Biogipuzkoa) and Isabel Portillo (Colon Cancer Screening Programme of the Basque Country) in one of the largest controlled clinical trials carried out in Spain, in which the effectiveness of the two main strategies for colorectal cancer screening was compared over a period of ten years.

The study, published in The Lancet, shows that both strategies are similar in the detection of colorectal cancer and in their capacity to reduce the mortality rate associated with this tumour. “The study shows how population screening by means of faecal occult blood testing every two years reduces the colon cancer mortality rate in a similar way to colonoscopy offered every ten years,” explained Luis Bujanda. So it has been demonstrated that the faecal occult blood test, which is less invasive and more readily accepted by the population, is not inferior to colonoscopy in terms of reducing the mortality rate for colorectal cancer.

Very high participation by the population of Lasarte-Oria

The randomised clinical trial involved 57,000 men and women aged between 50 and 69 from eight autonomous communities or regions (Aragon, Canary Islands, Catalonia, Galicia, Madrid, Murcia, the Basque Country and Valencia). 4,700 of these individuals were invited to participate in Lasarte-Oria (Gipuzkoa). The participants were divided into two groups: one group was invited to undergo a colonoscopy, while the other group was invited to have the faecal immunochemical test (FIT) every two years (five in total). The main aim was to compare the mortality rate for colorectal cancer ten years later.

The overall results of the study showed that, at 40%, participation in screening was higher in the faecal occult blood test group, compared with the colonoscopy group, which was around 32%.  “‘Participation in Gipuzkoa was the highest in the study: the faecal occult blood test was accepted by 60% of those invited to do it, and a colonoscopy accepted by 44% of those invited to undergo it,” added Bujanda.

In actual fact, the results show that the mortality rate for colorectal cancer after 10 years was similar in both groups: 0.22% in the colonoscopy group and 0.24% in the faecal immunochemical test group. The incidence rate of these tumours was also similar. This indicates that the test is just as effective as colonoscopy in reducing the mortality rate for colorectal cancer within the framework of screening programmes.

The researchers stressed that “these results are highly significant as they demonstrate that a non-invasive test such as the faecal occult blood test can be a viable alternative to colonoscopy for colorectal cancer screening. This could increase participation in screening programmes, since the faecal immunochemical test is more convenient and less invasive for those who want to participate.

The study reinforces the importance of screening programmes

“The impact of this study is huge in determining how a simple, cost-effective test can significantly reduce the mortality rate in a disease that is of major importance, and which has led to the spread of population screening in countries around the world, preventing many deaths and high costs due to advanced diseases,” added Bujanda. The researcher stressed that “the 10-year mortality rate was reduced by more than 78% in people participating in the screening programme”.

Without going any further, since the Basque Autonomous Community’s screening programme was launched in 2009, and in which the population between 50 and 69 years of age is invited to have a faecal occult blood test every two years, “more than 1,000 deaths have been prevented and the mortality rate has decreased by more than 28%”, Bujanda pointed out, “which has made it possible to reduce the overall death rate by one percentage point”. He also highlighted the fact that “participation in excess of 70% in this screening in our community is one of the highest in the world”. In Lasarte-Oria, while the study was ongoing, “13 colon cancer deaths were prevented and intensive treatment (surgery-chemotherapy-radiotherapy) was avoided for more than 40 people,” he added.

Bujanda was keen to point out that the study presented “was carried out independently of the pharmaceutical industry”. He added that they had received public funding (Ministry of Health, Basque Government, Provincial Council of Gipuzkoa, EITB maratoia), private funding (Spanish Association Against Cancer, Kutxa Social Outreach Programme) on a competitive basis and funding from Dr Luis Bujanda’s research group awarded through CIBER. “That money covered the cost of more than 1,200 colonoscopies carried out in Gipuzkoa with the collaboration of the Instituto Onkologikoa and Policlínica Gipuzkoa.”

Additional information

The study was coordinated by Dr Antoni Castells, the healthcare director of the Hospital Clínic Barcelona, head of the gastrointestinal and pancreatic Oncology group at IDIBAPS and CIBERehd, and professor of gastroenterology at the University of Barcelona; and Dr Enrique Quintero, a gastroenterologist at the University Hospital of the Canary Islands and professor at the University of La Laguna in Tenerife. The project, by the name of COLONPREV, was also co-funded by the Carlos II Institute for Health.