Role of thyroid stimulating hormone suppression in the management of thyroid cancer.

Well-differentiated thyroid cancers (papillary, follicular, and some Hurthle cell tumors) contain membrane receptors for TSH. Responsiveness of these tumors to TSH stimuli is documented by increased radioactive iodine uptake, secretion of thyroglobulin, increase in thyroid size, and potential progression to an anaplastic type. Although TSH suppression has a variable effect on the growth of existing tumors and the incidence of recurrent disease, there is a sound rationale for long-term TSH suppression in all patients with differentiated tumors of the thyroid. The ultrasensitive TSH test permits ready monitoring of the adequacy of thyroxine dosage. The cost is minimal (approximately $.10/day) and the risks are negligible if one assumes the avoidance of hyperthyroxinemia.