TSH-suppressive treatment in differentiated thyroid cancer. A dogma under review

TSH-suppressive therapy (ST) is part of the treatment protocol for differentiated thyroid carcinoma (DTC). There is however little evidence of its clinical effectiveness. On the other side, ST is not free from side effects related to the subclinical hyperthyroidism status induced in patients for a long time period. Because of this, widespread use of ST in all patients has recently been questioned, and individualized treatment based on the characteristics of each particular case has been proposed. Action of thyroid hormones (THs) depends on their binding to specific nuclear receptors. However, a second pathway mediated by a membrane receptor located in integrin α(V)β(3) has recently been established. It has been postulated that the proliferative and angiogenic effects attributed to THs would depend on this second mechanism. It is not known whether the tumorigenic action shown in other neoplasms may have an impact on DTC. The objective of this study was to review the relationship between ST and cancer, particularly as regards tumor evolution and occurrence of second primary neoplasms. One of the future challenges in the field of DTC will be to establish the specific role of TSH and THs in malignant thyroid cells, in order to be able to define more optimized therapeutic schemes.