How Effective is Thyroid-Stimulating Hormone Suppression?

May 7th 2016

Thyroid-stimulating hormone suppression therapy is a common part of thyroid cancer treatment, and it is used to control the growth of residual malignancies after the main tumor has been removed. It is also used to prevent the growth of microscopic tumors that cannot be detected and removed. Thyroid-stimulating hormone suppression therapy is appropriate for some types of cancer, but its effectiveness has been called into question for certain other types. Knowing when thyroid-stimulating hormone suppression therapy is used and how it works to fight cancer helps thyroid cancer patients take charge of their treatment and improves long-term outcomes.

Types of Thyroid Cancer

Thyroid cancer occurs in several forms, which are generally grouped into two categories: differentiated and undifferentiated. Differentiated cancers are by far the most common, with papillary thyroid carcinoma and follicular thyroid carcinoma accounting for around 80 percent of all thyroid malignancies. Fortunately, effective treatments have been developed for differentiated carcinomas, and mortality rates for them are low. The less common undifferentiated cancers are more difficult to treat, with some, such as anaplastic thyroid carcinoma, having no standardized treatment at all and a five-year survival rate of only 5 percent.

When Thyroid-Stimulating Hormone Suppression Therapy Is Appropriate

Treatment for differentiated thyroid carcinomas usually consists of ablation, chemical or surgical, to reduce the size of the tumor. Thyroid-stimulating hormone suppression is used in conjunction with other therapies to prevent the regrowth of the cancerous cells in the thyroid. Hormone suppression therapy has proven effective in the treatment of high-risk cancers and in cases where there is a considerable risk of recurrence. It is also necessary to take thyroid hormone medications, such as levothyroxine, after the removal of the thyroid, which is sometimes necessary to completely eliminate the cancer.

When Thyroid-Stimulating Hormone Suppression Therapy Is Not Appropriate

As previously noted, certain types of undifferentiated malignancies, such as anaplastic thyroid carcinoma, have no standard treatment, and thyroid-stimulating hormone suppression therapy has not proved effective in ablating or controlling the growth of diseased tissue. Evidence is also generally lacking for thyroid-stimulating hormone suppression's effectiveness in the treatment of low-risk differentiated thyroid cancers, such as papillary thyroid carcinoma. In the case of papillary thyroid carcinoma, the risk of metastasis is low enough that the thyroid may be only partly removed, leaving enough tissue in place to maintain the patient's normal hormone production without the need for lifelong hormone therapy. Outcomes in either case, for both partial and total thyroid removal, are essentially identical, which suggests that a more conservative approach may be appropriate for such cases.

Thyroid-stimulating hormone suppression therapy is an effective tool for controlling the growth and spread of certain high-risk, differentiated cancers occurring in the thyroid. Low-risk carcinomas, as well as undifferentiated malignancies, have shown little to no response to thyroid-stimulating hormone suppression therapy, which militates against its use in these relatively rare types of thyroid cancer.

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