Prevalence of and risk factors for thyroid carcinoma in patients with familial adenomatous polyposis: results of a multicenter study in Japan and a systematic review

PurposeTo investigate the recent Japanese prevalence of thyroid cancer and its characteristics in familial adenomatous polyposis (FAP) patients, through the development of surveillance programs.MethodsThe subjects of this study were 282 (93.1%) FAP patients for whom information on thyroid cancer was available, from among 303 patients registered in the Retrospective Cohort Study of Familial Adenomatous Polyposis in Japan database. We evaluated the prevalence and risk factors for thyroid cancer and integrated and/or compared our findings with those of previous reports, using a systematic review, including a meta-analysis.ResultsThyroid cancer was diagnosed in 16 women (11.4%) and 2 men (1.4%), at 17-41years and 39-57years of age, respectively. The prevalence of thyroid cancer was 6.4%, with a female-to-male ratio of 8:1, which is comparable to reports from other countries. A young age of <33years at the FAP diagnosis and female gender were identified as independent risk factors for thyroid cancer.ConclusionsFAP-associated thyroid cancer predominantly affects young women, both in Japan and other countries. Since FAP is generally diagnosed when patients are in their 20s or older, regular screening for thyroid cancer is recommended for all FAP patients, but especially women, from their early 20s.