Carcinoma of the thyroid gland: an explanation for its varying incidence in surgically removed nodular thyroid glands

The single thyroid nodule

Between November, 1966, and March, 1970, 2736 patients with single thyroid nodules were investigated at the Alexandra Hospital. Females were more frequently affected than males, with a ratio of females to males of about 7:1. The right lobe was one and a half times more frequently involved than the left. In both lobes the lower pole was six to eight times more commonly involved than the upper pole. Pathological data after surgical excision were available in 692 of these patients. Malignancy was proved in 81 cases. The overall incidence of carcinoma was 11.7 per cent. Malignant nodules were two to three times more frequent in persons aged below 20 and over 60 and in males than in females. The incidence of carcinoma in cold and warm nodules was 12.8 and 6.6 per cent respectively. No malignancy was foun in a hot nodule or in a toxic adenoma. The location of the nodule was not helpful in predicting malignancy. It is concluded that the incidence of malignancy in cold and warm single thyroid nodules in high, and for this reason surgical removal supplemented with replacement therapy is recommended.