Multiple Endocrine Neoplasia Type 2 (MEN 2)
Level of evidence: 5
Screening of at-risk individuals in kindreds without an identifiable RET mutation
MEN 2A: Risk-reducing thyroidectomy is not routinely offered to at-risk individuals if the disorder is unconfirmed. The screening protocol for MTC is an annual calcitonin stimulation test; however, caution must be used in interpreting test results because CCH that is not a precursor to MTC occurs in about 5% of the population.[12,13,136] In addition, there is significant risk of false-negative test results in patients younger than 15 years. Screening for pheochromocytoma and parathyroid disease is the same as described above.
FMTC: Annual screening for MTC, as for MEN 2A.
Level of evidence: 5
Treatment for those with MTC
Standard treatment for adults with MTC is surgical removal of the entire thyroid gland, including the posterior capsule, and central lymph node dissection. Children with MEN 2B having prophylactic thyroidectomy within the first year of life may not require central neck dissection unless there is radiological evidence of nodal disease. Likewise, children with MEN 2A or FMTC having prophylactic thyroidectomy before three to five years of age should not have a central neck dissection in the absence of radiological evidence of metastatic lymph node involvement. The ATA also recommends that MEN 2A and FMTC patients older than 5 years or asymptomatic MEN 2B patients older than 1 year have a preoperative basal calcitonin test and neck ultrasound. A basal calcitonin level over 40 pg/mL or thyroid nodules greater than or equal to 5 mm requires further evaluation, as the patient may have more extensive disease requiring nodal dissection. If an MEN 2B patient over the age of 1 year has nodules less than 5 mm or basal calcitonin less than 40 pg/mL, then total thyroidectomy may be sufficient therapy, but the ATA task force favors prophylactic central neck dissection without lateral compartment dissection in the absence of radiographic evidence of metastatic involvement (level C recommendation). See Table 3 for complete details.
Table 3. American Thyroid Association Management Guidelines for MEN 2A/FMTC and MEN 2Ba
FMTC = familial medullary thyroid carcinoma; MEN 2 = 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 the U.S. Preventive Services Task Force.
|Syndrome ||Age (y)||Nodal disease||Basal calcitonin (pg/mL) b||Nodule ? 5mm ||Lymph node dissection ||Strength of recommendationc|
|MEN 2A/FMTC||< 3-5 ||No||< 40 ||No ||No ||E|
|MEN 2A/FMTC||< 3-5 ||Yes||> 40 ||Yes||Yes||B|
|MEN 2A/FMTC||> 5 ||No||< 40 ||No ||No||E|
|MEN 2A/FMTC||> 5 ||Yes||> 40 ||Yes||Yes||B|
|MEN 2B||< 1 ||No||< 40 ||No ||No||E|
|MEN 2B||< 1 ||Yes||> 40 ||Yes||Yes||B|
|MEN 2B||< 1 ||No||< 40 ||No ||Yes||C|