# Medullary thyroid cancer

Source: https://onco.cc/cancers/medullary-thyroid-cancer/  
OnCo record `medullary-thyroid-cancer` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Medullary thyroid cancer comes from the calcitonin-making C cells, not the thyroid hormone cells, so radioactive iodine does not work. Surgery is the only cure, a quarter of cases run in families through the RET gene, and the RET-selective drug selpercatinib has transformed treatment of advanced disease.

## Summary

Medullary thyroid cancer arises from the parafollicular C cells and secretes calcitonin, which serves as its tumour marker. Germline RET mutations cause the hereditary forms (MEN2A, MEN2B and familial medullary thyroid cancer), and children who inherit them have the thyroid removed before cancer develops, timed by the mutation's risk level; most sporadic tumours carry a somatic RET M918T mutation, and a minority RAS mutations. Total thyroidectomy with central neck dissection is the only curative treatment, and calcitonin doubling time guides follow-up. For progressive advanced disease, vandetanib (2011) and cabozantinib (2012) were the first approved kinase inhibitors; selpercatinib, a RET-selective inhibitor, beat them in the LIBRETTO-531 trial and is now the standard for RET-mutant disease, with pralsetinib as an alternative. Phaeochromocytoma must be excluded before any thyroid surgery in MEN2.

## Fields

- Kind: Cancer
- Last checked: 2026-09-17
- Also known as: Medullary thyroid carcinoma; MTC
- Tags: subtype-page
- Group: endocrine
- Burden: Two to four percent of thyroid cancers; a quarter are inherited through a RET mutation in the multiple endocrine neoplasia type 2 syndromes; ten-year survival ranges from above 95 percent for disease confined to the thyroid to under half once distant spread has occurred.
- Subtypes: Sporadic (about 75 percent); Hereditary: MEN2A (with phaeochromocytoma and hyperparathyroidism); Hereditary: MEN2B (mucosal neuromas, marfanoid habitus, early aggressive disease); Familial medullary thyroid cancer only
- Biomarkers: Calcitonin and CEA (diagnosis, follow-up and doubling time); Germline RET testing in every patient; Somatic RET M918T; RAS mutations in RET-negative tumours

## Standard of care

- Hereditary RET carriers: Prophylactic total thyroidectomy in childhood, timed by the RET codon risk category (before age one in MEN2B). ([RET](https://onco.cc/targets/ret/), [Multiple endocrine neoplasia syndromes (MEN1, MEN2, MEN4)](https://onco.cc/cancers/multiple-endocrine-neoplasia/))
- Localised disease: Total thyroidectomy with central compartment dissection, lateral dissection when nodes are involved; no radioactive iodine; levothyroxine replacement only. ([Thyroid cancer](https://onco.cc/cancers/thyroid/))
- Advanced RET-mutant disease: Selpercatinib first line (LIBRETTO-531 beat cabozantinib and vandetanib); pralsetinib as an alternative. ([Selpercatinib](https://onco.cc/drugs/selpercatinib/), [Pralsetinib](https://onco.cc/drugs/pralsetinib/), [RET](https://onco.cc/targets/ret/))
- Advanced RET-negative disease: Cabozantinib or vandetanib; external radiotherapy for local control; somatostatin analogues for diarrhoea from calcitonin. ([Cabozantinib](https://onco.cc/drugs/cabozantinib/), [Vandetanib](https://onco.cc/drugs/vandetanib/))

## State of the art

- Selpercatinib gave a response rate near 70 percent and much longer progression-free survival than the older multikinase drugs, with fewer side effects.
- Genetic testing and prophylactic surgery have made hereditary medullary cancer a preventable disease in tested families.
- Calcitonin doubling time is one of the most reliable prognostic tools in any cancer.

## Open problems

- No cure once the disease has spread beyond the neck.
- Resistance mutations to RET inhibitors (G810) are emerging.
- RET-negative sporadic disease has no targeted option.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Medullary_thyroid_cancer
- Wikipedia: https://en.wikipedia.org/wiki/Medullary_thyroid_cancer

## Connected records

- targets: [RET](https://onco.cc/targets/ret/)
- drugs: [Cabozantinib](https://onco.cc/drugs/cabozantinib/), [Pralsetinib](https://onco.cc/drugs/pralsetinib/), [Selpercatinib](https://onco.cc/drugs/selpercatinib/), [Vandetanib](https://onco.cc/drugs/vandetanib/)
- cancers: [Multiple endocrine neoplasia syndromes (MEN1, MEN2, MEN4)](https://onco.cc/cancers/multiple-endocrine-neoplasia/), [Thyroid cancer](https://onco.cc/cancers/thyroid/)

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