Familial Non‐Medullary Thyroid Cancer: A Matched‐Case Control Study

OBJECTIVES: Familial non-medullary thyroid cancer (FNMTC) is a newly recognized disease entity and can be distinguished from the more common sporadic non-medullary thyroid cancer. The purpose of this study was to determine some of the potential distinguishing features of FNMTC. STUDY DESIGN: Retrospective association study and matched-case control study. METHODS: Five hundred forty-three cases of well-differentiated follicular origin thyroid cancers were identified and collected in a database. Among this population, 24 cases of FNMTC were identified. A case of FNMTC was defined as a patient with the following two criteria: a well-differentiated follicular origin thyroid cancer and at least one first-degree relative with a well-differentiated epithelial origin thyroid cancer. The unmatched sporadic and FNMTC groups were compared using t test, Phi test, Cramer V test, and Pearson and Spearman correlation tests. Twenty-four FNMTC cases were matched to 24 sporadic cases based on age, gender, stage of disease at presentation, and tumor size. Clinicopathologic features, management, and outcome were analyzed statistically using a matched-proportional z test. Disease-free survival and disease-specific survival were analyzed using log-rank test and the Kaplan-Meier function. A P-value less than .05 was considered statistically significant. RESULTS: : There was no significant difference in ionizing radiation exposure, disease multifocality, surgical management, or recurrence between the sporadic and FNMTC patients. Although FNMTC patients tend to have improved disease-free survival and disease-specific survival, the difference was not significant at the 5% level. CONCLUSION: Although FNMTC is characterized by strong family history, these patients do not tend to have worse prognosis.