What are the implications of brain metastases of papillary thyroid cancer (PTC)?

From the Guidelines

Brain metastases from papillary thyroid cancer (PTC) should be managed with a multidisciplinary approach, prioritizing surgical resection and external beam radiotherapy as the primary treatment options, as they offer the best chance of improving morbidity, mortality, and quality of life. According to the most recent and highest quality study available, which is the NCCN guidelines insights: thyroid carcinoma, version 2.2018 1, the management of brain metastases in PTC involves a combination of surgery, radiation therapy, and systemic treatments.

Key Considerations

• Surgical resection should be considered when feasible, followed by stereotactic radiosurgery (SRS) or whole brain radiation therapy (WBRT) 1.
• Radioactive iodine (RAI) therapy with I-131 may be beneficial if the metastases are iodine-avid, though the blood-brain barrier can limit uptake 1.
• Systemic therapies, such as tyrosine kinase inhibitors like lenvatinib or sorafenib, have shown efficacy in iodine-refractory disease and may be considered for patients with progressive disease 1.
• TSH suppression therapy with levothyroxine should be maintained to achieve TSH levels below 0.1 mIU/L.

Monitoring and Prognosis

• Regular monitoring with MRI brain scans every 3-6 months, along with thyroglobulin levels and whole-body scans, is essential to assess treatment response 1.
• Prognosis remains guarded, with median survival typically ranging from 4-33 months after diagnosis of brain metastases, though outcomes have improved with newer targeted therapies and multimodal approaches 1.

Treatment Priorities

• The primary goal of treatment is to improve morbidity, mortality, and quality of life, and treatment options should be prioritized accordingly.
• The most effective treatment approach will depend on the individual patient's circumstances, including the extent of disease, performance status, and presence of symptoms.

From the Research

Brain Metastases of Papillary Thyroid Carcinoma (PTC)

• Brain metastases from PTC are rare, occurring in 0.1-5% of cases 2
• The prognosis for patients with brain metastases from PTC is generally poor, with a mean overall survival of 9.0 months 2 and 15 months 3
• Treatment options for brain metastases from PTC include:
  • Surgery: associated with a trend toward longer survival 4
  • Radiation therapy: whole brain external beam radiation therapy and gamma knife radiosurgery appear to play beneficial therapeutic roles 4
  • Radioiodine therapy: may be effective in collapsing fragile peritumoral vessels 5
• Imaging modalities used to screen for brain metastases from PTC include:
  • MRI: preferred imaging modality 3
  • CT: used in combination with MRI or other imaging modalities 6, 2
  • 18F-FDG PET/CT: used in combination with MRI and 131I-SPECT/CT 3
• Clinical presentation of brain metastases from PTC may include:
  • Signs of intracranial hypertension 6
  • Intratumoral hemorrhage 5, 2
  • Peritumoral edema 6

Treatment Outcomes

• Surgery followed by radiotherapy appears to be a good alternative for the treatment of brain metastases from PTC 6
• Local therapies, such as surgical resection and radiation therapy, appear to control brain metastases in the majority of patients with PTC 4
• Overall survival after diagnosis of brain metastasis is reported to be longer than that noted with other solid tumors, with a median survival of 17.4 months 4

Patient Characteristics

• Age at diagnosis: ranges from 33 years 6 to 72 years 5
• Duration from initial diagnosis to brain metastasis: ranges from 0 months 5 to 155 months 5
• Sex: both males and females are affected, with a reported mean age of 64.6 years for males and females combined 2