Study analyzes metastases of medullary thyroid cancer

Public health authorities are aware of the most common sites of medullary thyroid cancer (MTC) metastases, but a new study from France's Institut Gustave Roussy and the University Hospital in Tours has tabulated the prevalence of the more unusual sites to which the disease can spread.

Published in the journal European Abstracts, the report found that 21 percent of participants with MTC metastases experienced tumors in unusual locations, including the adrenal glands, brain, breast, skin, pancreas, peritoneum, prostate, retina and endometrium.

The most commonly cited sites of MTC metastasis - namely, the bones, lungs and liver - were also examined. Overall, 69 percent of patients had bone metastases, 65 percent had them in their lungs and 60 percent had metastases in the liver.

MTC is a relatively rare form of thyroid cancer. According to the University of California, San Francisco Medical Center, between 5 and 7 percent of thyroid tumors are diagnosed as medullary thyroid cancer.

By comparison, the most common type of thyroid carcinoma, papillary thyroid cancer (PTC), accounts for at least 70 percent of all cases of the disease, according to the Columbia University Department of Surgery.

The National Institutes of Health (NIH) notes that MTC is more likely than papillary tumors to spread to other areas of the body.

Correspondingly, the survival rate for people diagnosed with MTC is lower than it is for those with PTC. The NIH estimates that 86 percent of MTC patients live five years beyond their diagnoses. In all, 65 percent of people with the disease live a full decade beyond their diagnoses.

However, metastasized MTC tends to have a poorer prognosis. In the new study, the 10-year survival rate for participants with metastatic MTC was just over 55 percent.

The team noted that patients with metastases in unusual sites had a 10-year survival rate of approximately 54 percent, indicating that MTC metastasis in uncommon sites was not associated with a poorer prognosis, compared to other MTC metastases.

The National Cancer Institute (NCI) emphasizes that metastatic MTC requires more than a simple thyroidectomy. Most patients with distant tumors will undergo chemotherapy or radiation treatment to eradicate cancer cells that have migrated beyond the bounds of the thyroid gland.

All told, nearly 45,000 Americans are diagnosed with some form of thyroid cancer every year, the NCI reports, adding that early detection - especially prior to the spread of tumor cells to distant sites - is crucial for improving the odds of survival and recovery.