Present status of prophylactic thyroidectomy in children with multiple endocrine neoplasia 2 in Japan: An overview article from a nationwide survey of the Japanese Society for Pediatric Endocrinology

Abstract

Multiple endocrine neoplasia type 2 (MEN2) is caused by germline mutations in the RET gene. Medullary thyroid carcinoma (MTC) with MEN2 has almost complete penetrance. MTC has a high frequency of postoperative recurrence. Hereditary MTC arises at a young age. Moreover, the risk of hereditary MTC increases with age.

Prophylactic thyroidectomy for MTC during early childhood in patients with MEN2 is recommended worldwide. Prophylactic thyroidectomy in patients with MEN2 is considered to be the best approach for avoiding recurrence; however, thyroidectomy during early childhood has a higher frequency of postoperative complications. Previous studies, including ours, reported that prophylactic thyroidectomy may decrease recurrence and postoperative complications in pediatric patients with MEN2. Prophylactic thyroidectomy is total thyroidectomy without lymphadenectomy when the lesion is considered to be limited to the thyroid. Therefore, prophylactic thyroidectomy has achieved a lower frequency of postoperative complications in early childhood.

In Japan, prophylactic thyroidectomy is not covered by the national health insurance system, which, in combination with the difficult balance between preventing recurrence and postoperative complications, results in most children not undergoing prophylactic resection. Hence, early calcitonin level-based thyroidectomy that is not based on age may reduce postoperative complications and improve the prognosis of pediatric patients with MEN2 in Japan due to large heterogeneity in the age of onset and aggressiveness of MTC.