Association between the age and the development of colorectal cancer in patients with familial adenomatous polyposis: a multi-institutional study

To investigate the incidence of colorectal cancer among familial adenomatous polyposis (FAP) patients by phenotype using the latest modalities. We collected data on 303 patients who underwent surgery for FAP at one of 23 institutions between 2000 and 2012. The incidence of colorectal cancer was investigated by phenotype. Colorectal cancer was diagnosed in 115 (38.0 %) of the 303 patients. Overall, colorectal cancer with the attenuated, sparse, and profuse phenotypes was diagnosed at 30, 31, and 28 years of age, respectively, in 10 % of the patients and at 59, 48, and 41 years of age, respectively, in 50 % of the patients (P = 0.013). The patients with colorectal cancer were older than those without colorectal cancer for all phenotypes. The optimal cut-off age for predicting the development of colorectal cancer in the attenuated, sparse, and profuse phenotypes was 46, 31, and 27 years, respectively. Patients with profuse and sparse phenotypes should undergo prophylactic proctocolectomy before their mid-to-late 20 s. On the other hand, the timing and type of surgery for patients with attenuated FAP (AFAP) should be decided individually with reference to the colonoscopic findings.