Malignant tumors in families of thyroid cancer patients.

A case-control study comprised 177 patients with various types of thyroid cancer and the same number of hospital controls individually matched by age, sex and place of residence. Malignant tumors were more frequent among first and second degree relatives of cases as compared to controls. The odds ratio (95% confidence interval) was 2.43 (1.33-4.44) and 5.33 (1.77-16.01) respectively. The most frequent were cancers of uterus and stomach with odds ratio of 6.00 (1.61-22.36) and 9.00 (1.64-49.35). Thyroid cancer was present only in first-degree relatives of two cases and none of controls.