Prophylactic colectomy at a premalignant stage is the cornerstone of familial adenomatous polyposis treatment (FAP). In children with FAP, colonoscopy monitoring is advised prior to surgery. The purpose of this study was to investigate the natural history of FAP in children by assessing adenoma development and variables influencing colectomy timing. Patients with FAP who were less than 18 years old at the time of their first surveillance colonoscopy and had had more than one colonoscopy were identified. Data on demographics, endoscopy, genetics, and surgery were obtained. While accounting for any polypectomies performed during the research period, cumulative adenoma counts were obtained. There were 84 patients identified, with 83 having a family history of FAP. Despite rectal sparing, 67 patients had 100 adenomas and 29 had colonic polyps detected on their first colonoscopy. The average polyp advancement rate per patient was 12.5 polyps per year. 41 of the 45 patients who had surgery had colectomy with ileorectal or ileal distal sigmoid anastomosis. Polyp progression had no effect on the surgical option chosen by any of the patients.

Findings show that the majority of children under monitoring have rather constant adenoma numbers. Tailored monitoring intervals based on phenotype are a more suitable method, according to recently published guidelines.