Age- and Gender-Specific Risk of Thyroid Cancer in Patients With Familial Adenomatous Polyposis.

CONTEXT The cribriform-morula variant of papillary thyroid carcinoma (CMV-PTC) is a rare variant of PTC and is associated with familial adenomatous polyposis (FAP). However, the incidence and the nature of CMV-PTC among FAP patients have not been well characterized. OBJECTIVE The aim of this study was to determine the incidence and characteristics of thyroid cancer screened by neck ultrasonography for FAP patients. Design, Patients, and Intervention: A total of 129 FAP patients were included in this study. Neck ultrasonography was performed using a 12.0-MHz transducer probe. Germline APC gene mutation was examined for by the protein truncation test or DNA sequencing methods. DESIGN, PATIENTS, AND INTERVENTION A total of 129 FAP patients were included in this study. Neck ultrasonography was performed using a 12.0-MHz transducer probe. Germline APC gene mutation was examined for by the protein truncation test or DNA sequencing methods. RESULTS Twenty-one patients (16.3%) had solid nodules, and 24 patients (18.6%) had benign cystic nodules. In total, PTC was found in 11 patients (16% of the women and 0% of the men), 8 of which were CMV-PTC and the rest were classical PTC. In 17 female patients with thyroid nodules, CMV-PTC occurred in 8 of 9 patients who were 35 years age or younger but in none of the 8 patients who were older than 35 (P = .0004 by Fisher's exact test). The APC germline mutations in 8 patients with CMV-PTC were present at the 5' side of the profuse type of FAP region (codons 1249-1330). CONCLUSIONS The prevalence of CMV-PTC in FAP patients was higher than previously reported and this type of tumor was found preferentially in younger (under age 35) female patients with FAP in this cohort.