The Barcelona Colorectal Cancer Early Detection Programme (PDPCCR) is aimed at women and men aged 50 to 69. Participation consists of performing an immunochemical faecal occult blood test (iFOBT) every two years. When the result of this test is positive, a screening colonoscopy is recommended.
A study by the Clínic-IDIBAPS, published in the journal Gastroenterología y Hepatología, highlights that, despite the proven effectiveness of screening, there is still a part of the population that does not complete the recommended diagnostic process and does not undergo the screening colonoscopy. When the result of the iFOBT is positive, the colonoscopy is the next step to confirm or rule out the presence of lesions or tumours.
But, why does that happen?
A key step after a positive result
Multiple pieces of evidence show that with the PDPCCR there has been a reduction in the mortality rate from colorectal cancer. However, several studies have shown that not undergoing this test increases the risk of dying from colorectal cancer. For this reason, European guidelines state that at least 86% of people with a positive result should undergo a colonoscopy.
Who refuses a colonoscopy?
The study focused on people in the Barcelona Esquerra Integrated Health Area (AISBE) who, between 2022 and 2023, had a positive screening test result but did not undergo a colonoscopy at the Clínic, or for whom there is no record of them having one at another centre.
The results show that this group presented a mean age of 60 years, a marked predominance of Spanish nationality and, in the vast majority, a high socioeconomic status.
Furthermore, the majority had no history of cancer, no family members with colorectal cancer, nor any symptoms that might support its presence.
Main reasons for refusal
Regarding the reasons for not undergoing the colonoscopy, the study identifies two main factors. On the one hand, a preference for having the procedure at another healthcare centre (21.09%), although it could not be confirmed whether it was ultimately carried out. And, on the other, the presence of serious illnesses or multiple pathologies (20.31%), which required prior medical authorisation.
These results point to the need to improve follow-up pathways, coordination and communication between centres, as well as to carry out an individualized assessment of the risk-benefit of the test according to the person’s state of health.
This study brings us closer to a better understanding of why some individuals do not undergo the recommended colonoscopy within the screening programme. “Although this is a very small number of participants, it is important to understand this population in order to focus efforts on ensuring that all individuals recommended to undergo a colonoscopy complete the screening process,” says Àngels Pozo, an Advanced Practice Nurse in Colorectal Cancer Screening, member of the IDIBAPS Gastrointestinal and Pancreatic Oncology research group and lead author of the study.
Implications for the future of screening
The study’s findings highlight that improving adherence to colonoscopy is key to increasing the effectiveness of early detection programmes.
In this regard, strengthening communication with participants, facilitating continuity of care and tailoring recommendations to each case can help reduce the number of people who do not complete the process.
Dr Antoni Castells, medical director of the Hospital Clínic Barcelona, head of the IDIBAPS Gastrointestinal and Pancreatic Oncology research group, and senior author of the study, explains that, “the proportion of people who do not agree to have a colonoscopy after a positive faecal occult blood test result is low, but it should be practically zero. Reducing this percentage and, above all, increasing participation in colorectal cancer screening programmes is our main objective.”
Reference study
Pozo A, Serradesanferm A, Rubio L, Pellisé M, Grau J, Torá-Rocamora I, Castells A. Factors associats al rebuig de la colonoscòpia després d’un resultat positiu en el cribratge de càncer colorectal. Gastroenterología y Hepatología. 2026.
