3. Medullary Thyroid Cancer (MTC): Understanding the Uncommon
Venturing into the less common types of thyroid cancer leads us to Medullary Thyroid Cancer, typically known as MTC. Despite its lower incidence, MTC carries unique characteristics that set it apart from other thyroid cancers. It constitutes about 2 to 3% of all thyroid cancer cases.
MTC begins its journey in the parafollicular cells (also known as C cells) of the thyroid gland. These cells are responsible for producing calcitonin, a hormone that plays a vital role in maintaining the body’s calcium balance. While calcitonin doesn’t play a direct role in metabolism like other thyroid hormones, it is crucial in keeping a stable body environment.
A distinguishing feature of MTC is its sporadic or familial occurrence. Approximately 75% of MTC cases are sporadic, appearing randomly without a known cause. The remaining 25% of cases are familial, passed down through generations, and are often associated with other endocrine disorders. This unique distribution highlights the importance of genetic counseling and testing in the management of MTC.
The causative factors of MTC vary depending on its sporadic or familial nature. The sporadic form of MTC is generally associated with mutations in the RET proto-oncogene. On the other hand, familial MTC is inherited and often linked to multiple endocrine neoplasia type 2 (MEN 2), a rare genetic condition. The genetic aspect of MTC underscores the necessity of understanding one’s family medical history.
MTC tends to present symptoms earlier than other types of thyroid cancer due to the high levels of calcitonin produced by the tumor. The most common symptoms include a lump in the neck, difficulty swallowing, and changes in voice. In some cases, patients might also experience diarrhea due to the effect of excessive calcitonin on the gastrointestinal tract. An early diagnosis of MTC can significantly improve treatment success and patient outcome. (3)
