Characteristics of 108 thyroid cancers detected by screening in a population with a history of head and neck irradiation.

One hundred and eight cases of thyroid cancer have been discovered as a result of screening 1712 individuals from a well defined population known to be at high risk because of prior head or neck irradiation for benign conditions. Of these 198 cancers, 43 (39.8%) were palpable, 27 (25.0%) were detectable by means of thyroid scintigraphy alone, and 38 (35.2%), referred to as incidental carcinomas, were found when the patients were operated on for lesions which approved to be benign. The most striking feature of these cancers was the high frequency of multicentricity (55%) and bilaterality (36%). This high frequency was found in clinically apparent as well as incidental cancers, and could not be accounted for by the operative pathologic techniques of investigation. Of 42 subjects reevaluated at our institution after a mean time of 38 months, 2 had definite and 2 had probable recurrent or residual thyroid disease. The postoperative thyroglobulin levels in subjects with thyroid cancer were proportional to the amount of thyroid tissue remaining. Follow-up evaluation of the entire group did not disclose any differences in the behavior of these thyroid cancers compared to those not associated with radiation.