Background
Evidence review and expert commentary on the role of external beam RT (EBRT) in medullary thyroid cancer (MTC), a neuroendocrine tumor of parafollicular C cells. Surgery (total thyroidectomy + central/lateral neck dissection) is the only curative treatment; reviews whether adjuvant or salvage EBRT improves locoregional control.
Interventions and follow up
Treatment: Adjuvant external-beam RT after surgery for high-risk MTC
Primary endpoint: Locoregional control and overall survival
mFollow up: Median 7+ yr
Primary endpoint: Locoregional control and overall survival
mFollow up: Median 7+ yr
Results
Locoregional control: Adjuvant EBRT can improve LRC in high-risk patients (T4, gross extrathyroidal extension, positive margins, pN1 with ECE, incomplete resection)
Technique: IMRT enables adequate dose with acceptable toxicity
Limitation of benefit: Not curative for distant metastases; does not lower circulating calcitonin/CEA; benefit confined to locoregional control
Technique: IMRT enables adequate dose with acceptable toxicity
Limitation of benefit: Not curative for distant metastases; does not lower circulating calcitonin/CEA; benefit confined to locoregional control
Adverse events
Neck EBRT toxicity: Esophagitis, dysphagia, xerostomia, neck fibrosis
Endocrine: Hypothyroidism (post-thyroidectomy patients already on replacement)
Planning constraints: Spinal cord and brachial plexus critical
Endocrine: Hypothyroidism (post-thyroidectomy patients already on replacement)
Planning constraints: Spinal cord and brachial plexus critical
Conclusions
EBRT should be considered for locally advanced MTC to optimize locoregional control — particularly T4 disease, ECE, positive margins, or incomplete resection. Not recommended as routine adjuvant for completely resected MTC without high-risk features.
Key Limitations
Retrospective single-institution data with no randomized comparison; selection bias (high-risk patients chosen for EBRT); benefit limited to locoregional control with no OS or systemic-disease impact; quantitative LRC/OS figures not detailed in source.
Clinical Context
Supports selective adjuvant EBRT for high-risk MTC. Systemic options for advanced/metastatic MTC include RET-targeted (vandetanib, cabozantinib, selpercatinib, pralsetinib) therapies; EBRT remains locoregional only.