OBJECTIVE: To evaluate the frequency of thyroid cancer and thyroid dysfunction in first-degree relatives of thyroid cancer patients, and to determine if there is a difference between familial and sporadic thyroid cancer. SUBJECTS AND METHODS: Fifteen first-degree relatives of seven families with at least two family members with thyroid cancer (TC) were compared with 128 first-degree relatives of 45 families with only one family member affected. Laboratory and ultrasound evaluation, fine-needle aspiration biopsy and thyroid surgery were used as normally done in clinical practice. RESULTS: Thyroid dysfunction was similar between the two groups. The frequency of TC and autoimmunity in the group that had two relatives with known thyroid cancer was higher, compared with the families that had sporadic thyroid cancer among their family members (40% vs. 2%, p = 0.0001). CONCLUSION: Frequency of TC increases when more than one member of the family is affected. These findings suggest that these relatives should be screened more frequently than individuals in families in which only one case of TC is observed.
Nonmedullary familial thyroid cancer; thyroid dysfunction; thyroid nodules
