THYROID-CARCINOMA FOUND AT PARATHYROIDECTOMY - ASSOCIATION WITH PRIMARY, SECONDARY, AND TERTIARY HYPERPARATHYROIDISM

BACKGROUND. Frequent reports of an association between primary hyperpa rathyroidism (HPT) and well differentiated thyroid carcinoma, compared with the few reports of associated secondary HPT and thyroid carcinom a, may have implications for different etiologic relationships between the conditions. METHODS. A retrospective review was performed of pati ents who underwent surgery for HPT between 1975 and 1996 in a single i nstitution. The prevalence of well differentiated thyroid carcinoma di agnosed at the time of parathyroidectomy (PTX) was compared for patien ts with primary, secondary, or tertiary HPT. RESULTS. There were 845 o perations for HPT in 824 patients. Twenty-two patients were found to h ave thyroid carcinoma at the time of PTX. Thyroid carcinoma was found in 2.6% of the patients with primary and 3.2% of the patients with eit her secondary or tertiary HPT (P = 0.550). Twenty-one of the patients had papillary carcinoma and 1 had a follicular carcinoma. Eighteen of the carcinomas were tl cm in size. A prior history of head and neck ir radiation was associated with the diagnosis of thyroid carcinoma at th e time of PTX (P < 0.001). Neither renal failure, organ transplantatio n, female gender, lymphocytic infiltration, nor follicular adenoma of the adjacent thyroid were significant in the association between HPT a nd thyroid carcinoma CONCLUSIONS. These data suggest that the associat ion between thyroid carcinoma and HPT is coincidental and possibly rel ated to the closer surveillance of the thyroid gland due to PTX and of ten concomitant removal of thyroid tissue. Patients with HPT and a his tory of head and neck irradiation are at increased risk of thyroid car cinoma. (C) 1997 American Cancer Society.