All patients with thyroid carcinoma seen a t T h e University of Texas M. D. Anderson Hospital and T u m o r Institute at Houston between March 1944 and June 1968 were studied to determine the incidence of a second malignant tumor either before or after the diagnosis of thyroid cancer. Additionally, those patients having thyroid cancer as the initial cancer were studied to determine their risk of developing a second malignant tumor. Analysis of the latter was by the patient-year method. Results showed that thyroid cancer patients have an increased number of second primary malignant tumors, and that they have a higher risk of developing a second primary after the diagnosis of thyroid cancer than the general population of the state of Connecticut. Possible explanations for these findings are discussed.
HE PRESENCE OF MULTIPLE PRIMARY MA-
T lignant neoplasms in one person has been a subject of interest for many years.5~ 9 Specific studies have dealt with malignant disease of the viscera in patients who have various types of skin carcinoma.1Q Shimaoka and assoc i a t e ~' ~ reviewed their own cases and others in the literature on primary carcinomas of the thyroid associated with other primary tumors. Certain patterns, i.e., association of pheochromocytomas and solid (medullary) carcinoma of the thyroid, have been described in groups of patients.'. 14 or in families.l? 3, 16 The purpose of this study was to determine if patients with thyroid cancer have a higher incidence of associated second primary malignant tumors and to determine the risk of developing