Risk of malignant tumors in first-degree relatives of patients with differentiated thyroid cancer -- a hospital based study.

In presented study the risk of incidence of familial differentiated thyroid cancer as well as the risk of other malignant tumors in families of DTC patients was evaluated. 999 patients with differentiated thyroid cancer and 825 persons without any history of malignant disease were evaluated on the occurrence of malignant neoplasm within their families. Information about 6614 first degree relatives of DTC index patients and 4939 first degree relatives of control persons were recorded. The incidence of cancers at various sites was compared between first-degree relatives of index patients and control persons and odds ratio with 95% confidence intervals (CI) were calculated for thyroid cancer and other cancer sites. Within 999 families of thyroid cancer index patients 23 families with more than one case of DTC were found. The risk of the development of thyroid cancer in the first degree was 6 (95% CI 1.8-19) times greater in the index group than in the control group. No increased risk for development of other malignancies was observed. Results of our study confirm previous reports of increased risk of thyroid cancer in first-degree relatives of differentiated thyroid cancer patients. However, the relatively small number of first-degree relatives affected with thyroid cancer (24/6614) does not justify at present any screening in the first-degree relatives of patients affected with differentiated thyroid cancer. Simultaneously, no increased risk of other malignant neoplasm was observed in the differentiated cancer families.