Medullary Thyroid Cancer (MTC) is a rare form of thyroid cancer, making up about 1% to 5% of all thyroid cancer cases. This cancer originates from the parafollicular C cells of the thyroid gland, which produce the hormone calcitonin. Understanding MTC survival rates involves examining factors influencing its progression and patient outlook.
Factors Influencing Medullary Thyroid Cancer Survival
Several elements influence MTC survival rates, indicating a varied prognosis. The extent of the cancer at diagnosis—localized, regional, or distant—significantly impacts outcomes. Localized cancer remains confined to the thyroid; regional disease has spread to nearby lymph nodes; and distant cancer has metastasized to other parts of the body, such as the lungs, liver, or bones. Patients diagnosed with more advanced stages generally face a less favorable prognosis.
Patient age at diagnosis also plays a role, with older individuals often having a worse prognosis. Tumor characteristics, including size and aggressiveness, further contribute to survival variability. Larger tumors and those exhibiting more aggressive behaviors tend to have less favorable outcomes.
MTC can be sporadic (about 75% of cases) or hereditary, often linked to Multiple Endocrine Neoplasia (MEN) type 2 syndromes. Hereditary forms, especially when found through genetic screening, may be diagnosed earlier, leading to better outcomes.
Medullary Thyroid Cancer Survival Statistics
Survival statistics for MTC provide a general overview of patient outcomes, typically expressed as relative survival rates. A relative survival rate compares the survival of individuals with MTC to that of people in the general population who do not have the cancer, matched for age and sex. For instance, a 5-year relative survival rate of 90% means that people with MTC are about 90% as likely to live for at least 5 years after diagnosis as people without the cancer. These rates do not predict an individual’s specific outcome but offer a broad perspective.
Data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program categorize MTC into three stages for survival analysis: localized, regional, and distant. For localized MTC, the 5-year relative survival rate is over 99%. For regional disease, where cancer has spread to nearby lymph nodes, the 5-year relative survival rate is around 94%. For distant MTC, the 5-year relative survival rate significantly decreases to about 50%. These figures are based on patients diagnosed between 2015 and 2021 and represent the most current available data.
Treatment Approaches and Prognosis
The primary treatment for MTC, especially in localized or regional stages, is extensive surgical removal. This typically involves a total thyroidectomy, removing the entire thyroid gland, often with lymph node dissection in the neck to remove affected lymph nodes. For hereditary forms identified through genetic testing, a prophylactic thyroidectomy may be performed before cancer symptoms appear, offering a long-term cure. Complete surgical removal offers the best chance for a favorable prognosis.
Other treatments are considered based on the disease’s extent and progression. External beam radiation therapy may be used after surgery for more advanced cases, such as stage 3 or 4 cancers, or if the cancer has spread to many nearby tissues. While radiation can help control local recurrence, its impact on overall survival is still debated.
For advanced or metastatic MTC, targeted therapies, specifically multikinase inhibitors like vandetanib or cabozantinib, are utilized. These drugs block specific pathways cancer cells use to grow and spread, aiming to improve outcomes or manage symptoms in progressive or widely spread cases. Selpercatinib is another targeted therapy approved for advanced or metastatic MTC with specific RET mutations.
Chemotherapy is generally reserved for metastatic MTC when targeted therapies are not effective or tolerated, usually as a palliative measure.
Monitoring and Long-Term Outlook
Following initial MTC treatment, ongoing monitoring is a regular part of patient care. This involves consistent follow-up appointments and blood tests to measure levels of calcitonin and carcinoembryonic antigen (CEA). Calcitonin is a specific MTC marker; its levels can indicate residual or recurrent cancer. An undetectable calcitonin level after surgery is associated with a high chance of long-term disease-free survival.
Increasing CEA levels can also suggest more aggressive disease. Imaging studies, such as ultrasound, CT scans, or PET scans, are also used to detect any recurrence or spread of the cancer.
While complete remission is the goal, recurrence is possible, with management depending on where the cancer returns. Early diagnosis of recurrence is important for effective treatment.
The long-term outlook for MTC patients varies, with initial clinical stage remaining a strong predictor of future mortality even decades after diagnosis.