Inherited Medullary Thyroid Carcinoma (MTC)

The decision regarding prophylactic thyroidectomy is based not only on mutational analysis but also on calcitonin levels.

Children with inherited MTC should be managed by teams of experienced physicians and surgeons in tertiary care centers.

The NCCN guidelines for management of these patients are shown in first figure. The ATA guidelines are generally similar but include the use of risk stratification system (ATA – HST, ATA – H, ATA – MOD) to determine timing of surgery.

In addition, due to the heterogeneity in the age of onset and aggressiveness of MTC even among different families with the same mutation and within individual families having the same RET mutation, the ATA guidelines also incorporate calcitonin levels to determine timing of surgery.

Children with ATA-HST category mutations (M918T) should have a thyroidectomy prior to age 1, and some groups suggest it should be in the first months of life, as shown in the figure.

The NCCN guidelines also include codon 883 or compound heterozygous (V804M + E805K, Y806C, or S904C) mutations in this early surgery group.

In the absence of known lymph node spread, the performance of a central neck dissection in the ATA guidelines is contingent upon parathyroid gland identification and determining whether they can be preserved in situ or reimplanted.

The NCCN guidelines also suggest consideration of prophylactic bilateral central neck dissection and prophylactic lateral neck dissection if the tumor is greater than 0.5 cm.

Children in the ATA-H category are generally advised to undergo thyroidectomy at age 5 (or earlier based on calcitonin levels).

In contrast to the ATA guidelines, the NCCN guidelines include children with not only codon 634 mutations but also those at codons 609, 611, 618, 620, 630, 768, 790, 791, 804, or 891.

Patients with ultrasonographic evidence or direct visualization of lymph node metastases at surgery or calcitonin levels above 40 pg/mL are also candidates for central neck dissection.

The NCCN guidelines suggest considering an ipsilateral prophylactic neck dissection if there is high-volume disease in the central neck or the tumor is greater than 1 cm.

Children in the ATA-MOD category are followed at 6 month or yearly intervals with physical examination, neck ultrasonography, and serum calcitonin measurements starting at around age 5.

The timing of surgery is based on the detection of an elevated basal calcitonin level.

If there are concerns regarding long-term follow-up, thyroidectomy may be performed at around age 5, similar to the NCCN guidelines.

With respect to other tumors, children in the ATA-H and ATA-HST categories should undergo screening for HPT and pheochromocytomas (with plasma metanephrines and normetanephrines or 24-hour urine studies for the same) starting at age 11 (if not tested earlier), whereas this can be delayed until age 16 in children in the ATA-MOD category.

Imaging by abdominal CT or MRI is indicated if biochemical tests are abnormal.

All patients with MEN2A or MEN2B must be screened for pheochromocytomas, and these tumors must be resected prior to any neck surgery.

Laparoscopic or retroperitoneoscopic adrenalectomy is preferred, and subtotal adrenal resection to preserve cortical function should be considered.

In patients with HPT, only visibly enlarged or abnormal glands are resected. If all the glands are abnormal, either subtotal resection or total parathyroidectomy with heterotopic reimplantation (into the nondominant brachioradialis muscle) of parathyroid tissue is acceptable.

Rodrigo Arrangoiz MS, MD, FACS is an expert in the management of thyroid diseases and is a member of Sociedad Quirúrgica S.C at the America British Cowdray Medical Center.

Training:

• General surgery:

• Michigan State University:

• 2004 al 2010

• Surgical Oncology / Head and Neck Surgery / Endocrine Surgery:

• Fox Chase Cancer Center (Filadelfia):

• 2010 al 2012

• Masters in Science (Clinical research for health professionals):

• Drexel University (Filadelfia):

• 2010 al 2012

• Surgical Oncology / Head and Neck Surgery / Endocrine Surgery:

• IFHNOS / Memorial Sloan Kettering Cancer Center:

• 2014 al 2016