In this context, two recent studies conducted within the framework of the COLONPREV project provide new data to better understand how colorectal cancer screening strategies work. This project is a large multicentre study coordinated by Clínic Barcelona–IDIBAPS, within the Clínic Barcelona Comprehensive Cancer Centre, and by Hospital Universitario de Canarias, with the participation of hospitals and screening programmes from several autonomous communities.
Colorectal cancer and the importance of screening
Colorectal cancer is one of the most common tumours and a leading cause of cancer‑related mortality. It often begins as polyps or precancerous lesions that grow slowly and can be detected and removed before they turn into cancer. For this reason, participating in screening programmes is essential to detect the disease early — or even prevent it altogether.
In Catalonia and the rest of Spain, screening is performed through a simple faecal immunochemical test (FIT) for occult blood. When the result is positive, the person is referred for a colonoscopy, which allows the colon to be examined and lesions removed.
This screening strategy has been validated through the COLONPREV study, coordinated by Dr. Antoni Castells, Medical Director of 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, gastroenterologist at Hospital Universitario de Canarias and Professor at Universidad de La Laguna in Tenerife. This study determined that FIT and colonoscopy are equivalent for detecting colorectal cancer.
Which lesions are detected with each strategy?
The first COLONPREV study, published as a research letter in Gastroenterology, analyses the characteristics of lesions detected when colonoscopy is performed in two different ways: as an initial screening test or following a positive FIT.
The study shows that people who undergo a colonoscopy after a positive FIT tend to have more advanced lesions. These lesions are generally larger and have histological features suggesting greater progression.
In contrast, when colonoscopy is used directly as the screening test, many more polyps overall are found, including small or early lesions that may never progress to a tumour or may take years to do so.
“This difference indicates that the two strategies complement each other: FIT acts as a selection tool to identify people more likely to have relevant lesions, while colonoscopy allows early treatment and the detection of other lesions that do not show up in the test,” notes Antoni Castells.
Screening is equally effective in men and women and across all age groups studied
The second study, published in United European Gastroenterology Journal, examines whether screening effectiveness varies according to sex or age. The study included more than 53,000 individuals aged 50 to 69, invited to undergo a one‑time colonoscopy or periodic FIT testing.
The results show that both FIT and colonoscopy reduce new cases of colorectal cancer and deaths from this disease to a similar extent in both men and women and across all age groups analysed. The study also confirms that participation is higher when FIT is offered, a key factor in reaching more people and therefore improving the programme’s impact.
Although men and older individuals have a higher initial risk of developing colorectal cancer, the benefit of screening is equally maintained across all groups.
A key message: participating in screening saves lives
In addition to the results of the two studies, a recent commentary published in Gastroenterology and signed, among others, by Dr. Antoni Castells, reflects on the role of different screening strategies and emphasises that the most important factor is not choosing a single test, but ensuring people take part in the screening programme.
According to the commentary, colonoscopy and FIT have complementary functions and are equally relevant within an organised screening system that prioritises accessibility, efficiency and public health impact.
“The goal is not to decide which test is ‘best’, but to ensure that people take part in the screening programme. Colonoscopy and FIT are complementary tools that, when used appropriately, help prevent more cases and reduce colorectal cancer mortality,” concludes Dr. Castells.
Study references:
Castells A, Quintero E, Pellisé M, Frías-Arrocha E, Hernández C, Serra-Burriel M; COLONPREV Study Investigators. Characteristics of Colonoscopy- and Fecal Immunochemical Test-Based Screen-Detected Premalignant Neoplastic Lesions: Results From the COLONPREV Study. Gastroenterology. 2026 Mar;170(3):627-630. doi: 10.1053/j.gastro.2025.10.018.
Castells A, Quintero E, Serra-Burriel M, Bujanda L, Castán-Cameo S, Cubiella J, Díaz-Tasende J, Lanas Á, Ono A, Coll-Vinent B, Frías-Arrocha E, Hernández C, Jover R, Andreu M, Carballo F, Morillas JD, Salas D; COLONPREV study investigators. Sex- and Age-Stratified Outcomes of Colonoscopy Versus Faecal Immunochemical Testing: Post-Analysis of the COLONPREV Study. United European Gastroenterol J. 2026 Mar;14(2):e70169. doi: 10.1002/ueg2.70169.
Ladabaum U, Weinberg DS, Castells A. Can Colonoscopy Still Be Promoted as the Best Choice for Colorectal Cancer Screening?. Gastroenterology. 2026 Mar;170(3):456-462. doi: 10.1053/j.gastro.2025.12.026.
