Clinical practice guideline. Diagnosis and prevention of colorectal cancer. 2018 Update.

This document updates the recommendations made by the Spanish Society of Family and Community Medicine and the Spanish Association of Gastroenterology for the diagnosis and prevention of colorectal cancer (CRC). In order to evaluate the quality of the evidence and determine the recommendation levels of the interventions, we used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology. This document establishes optimal delay intervals based on symptoms and the faecal immunochemical test (FIT) and recommends reducing the barriers for diagnostic confirmation in symptomatic subjects. With regard to CRC screening in the average-risk population, we propose strategies to achieve the universal implementation of organised CRC screening programmes based on biennial FIT and to increase the participation of the target population, including the involvement of Primary Healthcare. This Clinical Practice Guideline recommends universal screening for Lynch syndrome with mismatch repair proteins immunohistochemistry or microsatellite instability in incident CRCs and the use of gene panels in patients with adenomatous polyposis. It also updates the strategies to reduce the incidence and mortality of both CRC and other tumours associated with hereditary syndromes. Regarding non-hereditary familial CRC and surveillance after resection of adenomas, serrated lesions or CRC, we established the recommendations based on the attributable risk and the risk reduction of the proposed intervention. Finally, the document includes recommendations regarding surveillance intervals in inflammatory bowel disease and the attitude towards dysplasia.