Multiple Endocrine Neoplasia Type 2
Table 6. American Thyroid Association Management Guidelines for MEN2A/FMTC and MEN2Ba
|Syndrome||Age (y)||Nodal Disease||Basal Calcitonin (pg/mL)b||Nodule ≥ 5mm||Lymph Node Dissection||Strength of Recommendationc|
|FMTC = familial medullary thyroid carcinoma; MEN2 = multiple endocrine neoplasia type 2.|
|a Adapted from Kloos et al.|
|b Basal calcitonin values are applicable in patients older than 6 months.|
|c Based on grading definitions established by theU.S. Preventive Services Task Force.|
The ATA recommends lymph node dissection for patients meeting any one of the following criteria:
- Radiographic evidence of nodal disease.
- Basal calcitonin level greater than 40 pg/mL.
- A thyroid nodule greater than or equal to 5 mm.
Patients who have had total thyroidectomy will require lifelong thyroid hormone replacement therapy. The dosing of medication is age-dependent and treatment should be initiated based on ideal body weight. For healthy adults 60 years and younger with no cardiac disease, a reasonable starting dose is 1.6 to 1.8 µg/kg given once daily. Older patients may require 20% to 30% less thyroid hormone. Children clear T4 more rapidly than adults and consequently require relatively higher replacement by body weight. Depending on the age of the child, replacement should be between 2 to 6 µg/kg. It is important to note, however, that patients should be given replacement, rather than suppressive therapy. Since C-cell tumors are not TSH-dependent for growth, the T4 therapy for MTC patients therefore should be adjusted to maintain a TSH within the normal reference range.
There is no difference in survival between familial and sporadic forms of MTC when adjusted for clinicopathologic factors. Chemotherapy and radiation are not effective against this type of cancer,[3,209,210] although clinical trials (phases I–III) of various targeted molecular therapies are ongoing at selected centers. Some of these compounds have shown partial responses in a small percentage of patients, but most studies have demonstrated disease stability as the most favorable response.[211,212,213,214] The use of vandetanib is approved by the FDA for use in adult patients with progressive metastatic MTC who are ineligible for surgery. A phase III study found that progression-free survival was longer in patients who received the study drug than in those who received placebo. There was no demonstration of improved overall survival, however. Future studies will likely focus on the development of new targeted therapies and the use of combination therapy in MTC. (Refer to NCI's List of Clinical Trials for more information about these trials. Refer to the PDQ summary on Thyroid Cancer Treatment for more information about the treatment of thyroid cancer.)