Prophylactic Thyroidectomy for the Prevention of Medullary Thyroid Carcinoma
DESCRIPTION
Medullary thyroid cancer is surgically curable if detected before it has spread to regional lymph nodes. However, lymph node involvement at diagnosis may be found in up to 75% of individuals for whom a thyroid nodule is the first sign of disease. Medullary thyroid carcinoma often recurs and/or metastasizes despite complete thyroidectomy in those with positive lymph nodes. Thus, there is an emphasis on early detection and intervention in families affected by multiple endocrine neoplasia (MEN) types 2A and 2B or familial medullary thyroid cancer (FMTC). The development of invasive medullary thyroid cancer is usually preceded by C-cell hyperplasia, which can be detected by hypersecretion of calcitonin in response to a chemical challenge. Genetic assays for mutations have been used as an alternative to annual biochemical testing for C-cell hyperplasia in individuals with a known family history of MEN 2A, 2B, or FMTC. Annual biochemical screening can be stopped in those individuals who test negative for mutations. Individuals who test positive for mutations may undergo immediate prophylactic thyroidectomy or postpone thyroidectomy until biochemical tests suggest evolving medullary cancer.
Up to 9% of thyroid cancer (0.1% of all non-skin cancer) is classified histologically as medullary carcinoma. The familial cancer syndromes (MEN 2A, MEN 2B & FMTC) together are responsible for approximately one-fourth of the incidence of medullary carcinoma of the thyroid. Approximately 90% of the inherited medullary thyroid carcinoma occurs as MEN 2A, with MEN 2B and FMTC accounting for approximately 5% each. Over their lifetime, more than 95% of those who inherit a RET proto-oncogene point mutation will develop C-cell hyperplasia and/or medullary thyroid carcinoma if the gland is not removed before the disease is diagnosed by clinical symptoms. The average age of onset differs among the three inherited syndromes. Onset is less than 10 years of age for MEN 2B, near 20 years of age for MEN 2A, and between 40 and 50 years of age for FMTC. The inherited forms also differ in aggressiveness, with the tumors being most indolent in FMTC and most aggressive in MEN 2B.
POLICY
Prophylactic thyroidectomy for the prevention of medullary thyroid carcinoma is considered medically necessary if the medical appropriateness criterion is met. (See Medical Appropriateness below.)
See also: Genetic Testing for Medullary Thyroid Carcinoma
MEDICAL APPROPRIATENESS
Prophylactic thyroidectomy for the prevention of medullary thyroid carcinoma is considered medically appropriate for individuals whose genetic testing is positive for RETS proto-oncogene point mutations.
IMPORTANT REMINDER
We develop Medical Policies to provide guidance to Members and Providers. This Medical Policy relates only to the services or supplies described in it. The existence of a Medical Policy is not an authorization, certification, explanation of benefits or a contract for the service (or supply) that is referenced in the Medical Policy. For a determination of the benefits that a Member is entitled to receive under his or her health plan, the Member's health plan must be reviewed. If there is a conflict between the Medical Policy and a health plan, the express terms of the health plan will govern.
ADDITIONAL INFORMATION
It is important that individuals with MEN 2A and MEN 2B have pheochromocytoma excluded before undergoing thyroidectomy. Pheochromocytoma is a chromaffin cell tumor of the sympathoadrenal system that produces catecholamines.
SOURCES
Cobin, R. H., Gharib, H., Bergman, D. A., Clark, O. H., Cooper, D. S., Daniels, G. H., et al. (2001). AACE/AAES medical/surgical guidelines for clinical practice: management of thyroid carcinoma. Endrocrine Practice, 7 (3), 202-220. (113 articles and/or guidelines reviewed)
Kloss, R. T., Eng, C., Evans, D. B., Francis, G. L., Gagel, R. F., Gharib, H., et al. (2009). Medullary thyroid cancer: Management guidelines of the American Thyroid Association. Thyroid, 19 (6), 565-612. (398 articles and/or guidelines reviewed)
National Comprehensive Cancer Network. (2011). NCCN clinical practice guidelines in oncology™. Thyroid carcinoma (V.3.2011). Retrieved July 20, 2011 from http://www.nccn.org/professionals/physician_gls/pdf/thyroid.pdf.
Rosenthal, M. S., & Diekema, D. S. (2011). Pediatric ethics guidelines for hereditary medullary thyroid cancer. International Journal of Pediatric Endocrinology, 2011, 847603.
Skinner, M. A., Moley, J. A., Dilley, W. G., Owzar, K., DeBenedetti, M. K., & Wells, S. A. (2005). Prophylactic thyroidectomy in multiple endocrine neoplasia type 2a. The New England Journal of Medicine, 353 (11), 1105-1113.
ORIGINAL EFFECTIVE DATE: 5/1/2000
MOST RECENT REVIEW DATE: 9/22/2011
ID_BT
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