Current clinical practice for familial adenomatous polyposis in Japan: A nationwide multicenter study.

Introduction: In Japanese patients with familial adenomatous polyposis (FAP), colectomy tends to be postponed or avoided.

Aim: This study aimed to clarify the current clinical practice from a Japanese multicenter cohort study database.

Methods: We analyzed the records of 250 patients with non-dense FAP who did not require colorectal cancer removal. The clinical outcomes were compared between patients who received colectomy (n = 142) (Group A) and those who did not receive colectomy (n = 108) (Group B).

Results: The colectomy rate based on the age at the final follow-up examination was 46%, 60%, 54%, 65%, at ≤29, 30-39, 40-49, and ≥ 50 years, respectively ( = .11). The development of colorectal cancer did not differ between Groups A and B (25% vs 22%  = .67); however, colorectal cancer was diagnosed at the Tis stage in 88% of the patients with colorectal cancer in Group B, and 34% of the patients with colorectal cancer in Group A ( < .01). Regarding survival, all patients in Group B were alive at the final follow-up examination. In contrast, six patients in Group A died, including three patients with desmoid tumors and one with colon cancer.

Conclusion: Over one-third of patients with non-dense FAP (polyps ≤ 1000) in Japan did not receive colectomy at >30 years of age, and patients who managed without colectomy showed acceptable survival with the early diagnosis of colorectal cancer, and a very low incidence of desmoid tumor development, indicating that this approach represents a potential option for the management of selected non-dense FAP patients.