Key Factors That Influence the Risk of Medullary Thyroid Cancer
### Medullary Thyroid Cancer: What You Should Know
Medullary thyroid carcinoma (MTC) might not be the most common type of thyroid cancer, making up just 4% of all thyroid cancer cases in the U.S., but that still means approximately 1,000 people are diagnosed with it each year. Unfortunately, most diagnoses occur at Stage IV, where the survival rate drops to just 28%. This makes understanding the disease—and its primary risk factor—genetics, incredibly important.
#### A Genetic Mystery
Unlike many other cancers linked to lifestyle choices like smoking or environmental factors, genetics stands out as the only proven risk factor for medullary thyroid cancer. However, even then, genetics accounts for only about 25% of cases. The remaining 75% fall under the category of sporadic or isolated medullary thyroid cancer, with no known cause or additional risk factors identified. As Dr. Manisha H. Shah, a medical oncologist at Ohio State University Comprehensive Cancer Center, explained in an interview, “Basically, we don’t really know why they occur.”
Because of this genetic link, anyone diagnosed with medullary thyroid cancer—and their immediate family members—is encouraged to undergo genetic testing. A simple blood test can detect the presence of the RET proto-oncogene mutation, which is strongly associated with the disease. This method of genetic testing was pioneered by M.D. Anderson Cancer Center in 2009 and is now widely available at major medical facilities.
If the RET mutation is found, doctors can predict several factors: the likelihood of developing the cancer, the age it might appear, and how aggressive it’s likely to be. According to Dr. Shah, “It’s very clear that if you have the gene, you’re going to get the cancer. It’s only a matter of at what age and how aggressive the cancer will be.”
#### Recognizing and Treating MTC
Since medullary thyroid cancer currently has no other known risk factors, vigilance is critical for detection. In many cases, the disease is asymptomatic, but one key warning sign is a persistent lump in the neck. Other symptoms include chronic diarrhea or episodes of flushing, caused by hormones produced by the cancerous mass.
For individuals with the RET gene mutation but no signs of cancer yet, doctors may recommend a prophylactic thyroidectomy—a precautionary surgery to remove part or all of the thyroid gland. This approach is designed to prevent the mutation from progressing into cancer.
For those already diagnosed with medullary thyroid cancer, treatment typically involves two tyrosine kinase inhibitors (TKIs): vandetanib and cabozantinib. While both medications are considered effective, their benefits typically diminish after about two years. Researchers are actively conducting clinical trials to develop more advanced treatments.
#### A Hopeful Outlook
Advancements in genetic testing and diagnostic tools have significantly improved the ability to identify and manage medullary thyroid cancer in recent years. While current treatments still have limitations, ongoing research offers hope that more effective therapies will be available in the near future. Understanding the role of genetics and staying proactive with screenings can make a meaningful difference for those at risk.
