Medullary thyroid cancer surgery

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

Overview

Surgery is the mainstay of treatment for medullary thyroid carcinoma.

Surgery

Indications

In case of tumors < 1 cm in diameter or unilateral thyroid disease, total thyroidectomy with neck dissection (level VI) is indicated.^[1]
In case of tumors ≥ 1 cm in diameter or bilateral thyroid disease, total thyroidectomy with bilateral central neck dissection (level VI) is indicated.

The treatment of choice for primary medullary thyroid carcinoma, both sporadic or hereditary, is total thyroidectomy with systematic dissection of all lymph nodes of the central compartment. Total thyroidectomy is necessary as medullary thyroid carcinoma is multicentric in 65–90% of patients in multiple endocrine neoplasia type 2 and extensive central lymph node dissection has been reported to improve survival and recurrence rates compared to less aggressive procedures.^[2]^[3] Lymph node dissection of laterocervical compartments is reserved till the neck ultrasound suggests the presence of metastatic nodes.

Prophylactic thyroidectomy is advised in gene carriers to guarantee a definitive cure in these subjects.
During the Seventh International Multiple Endocrine Neoplasia Meeting in Gubbio in 1999, the risk of medullary thyroid carcinoma has been stratified in three categories according to the mutations of c-RET as following.

**Prophylactic Thyroidectomy**
Gene	Risk	Treatment
Children with MEN2B and/or c-RET codon 883, 918, 922	Highest risk of aggressive medullary thyroid carcinoma	Total thyroidectomy with central node dissection, within the first six months.
Children with any c-RET codon 611, 618, 620 or 634 mutations	High risk of medullary thyroid carcinoma	Total thyroidectomy should be performed before age of five years, with or without central node dissection.
Children with c-RET codon 609, 768, 790, 791, 804 and 891 mutations	Less aggressive and slowly growing medullary thyroid carcinoma	Operated at a later stage

The time of surgical treatment could be personalized and safely planned when the stimulated serum calcitonin becomes positive at the annual control, independently from the type of RET mutation and its associated level of risk. The follow-up controls should be more or less frequent in cysteine or noncysteine RET-mutated gene carriers, respectively. This strategy obviously implies a high compliance of the RET gene carriers to the scheduled follow-up with the advantage that young children can be treated later, sometime even after the puberty, close to the adulthood.
The following flowchart depicts the surgical management of medullary thyroid cancer.

Thyroxine should be supplemented for patients undergoing total thyroidectomy.^[4]
Serum calcitonin and carcinoembryonic antigen doubling time (CEA DT) are measured during post surgical follow-up.
Provacative pentagastrin or calcium test is administered and serum calcitonin level is measured.
If there is no significant elevation in serum calcitonin level, serum calcitonin is measured every 6 months for 2-3 years and then yearly.
If the calcitonin is below 150 pg/ml, ultrasound neck is recommended.
If the basal serum calcitonin is above 150 pg/ml, screening for distant metastasis is recommended.
The following flowchart depicts the post surgical management of medullary thyroid cancer.

References

Overview