Medullary Thyroid Cancer: An Overview

Hi, I’m Dr. James Wu, endocrine surgeon at UCLA Health. Today I want to talk to you about a rare type of thyroid cancer called medullary thyroid cancer—or MTC.

Most people are familiar with the more common types of thyroid cancer, like papillary or follicular cancer. But medullary thyroid cancer is different—it behaves differently, it’s treated differently, and in some cases, it even runs in families.

Let’s go over what makes it unique, and what you should know if you or someone you love has been diagnosed with it.

So first—what is medullary thyroid cancer?

Medullary thyroid cancer starts in a different kind of thyroid cell—the C cell—which is responsible for making a hormone called calcitonin. That’s different from the follicular cells that make thyroid hormone.

Because it comes from a different cell type, medullary thyroid cancer doesn't respond to the usual treatments we use for other thyroid cancers, like radioactive iodine. But the good news is: with the right surgery and follow-up, many patients do very well.

One of the first things we do when we diagnose medullary thyroid cancer is check two blood markers: calcitonin and CEA, or carcinoembryonic antigen. These are tumor markers that can help us understand how much cancer is present and how active it is.

We also recommend genetic testing to check for mutations in a gene called RET. That’s because in about 25% of cases, medullary thyroid cancer is part of an inherited condition—often called MEN2, or multiple endocrine neoplasia type 2.

If you do have a RET mutation, that’s important—not just for you, but for your family. It helps us plan your treatment and decide whether your relatives should also be tested.

Now let’s talk about treatment, and especially, why the first surgery is so important.

The initial surgery offers the best chance for cure. Unlike some other thyroid cancers where we can take a staged or gradual approach, with medullary thyroid cancer, we want to get it right the first time. That means removing the entire thyroid gland and the right lymph nodes, based on where the cancer is likely to spread.

To help plan that surgery, we perform a detailed neck ultrasound right here in clinic. That allows us to look carefully at the lymph nodes in the central and lateral compartments of the neck. If we see any concerning lymph nodes, we may recommend removing them at the same time as the thyroid.

Why does this matter? Because medullary thyroid cancer doesn’t respond to radioactive iodine, so surgery is really our only chance to remove all the disease. We want to avoid multiple surgeries if we can—so planning the correct extent of surgery upfront is critical.

The main treatment is a total thyroidectomy, which means removing the entire thyroid gland. We also typically remove lymph nodes in the central neck, and if the ultrasound shows any involvement in the side of the neck, we’ll include those as well.

After surgery, we track your calcitonin and CEA levels over time. If the surgery was successful, we expect those levels to drop significantly—sometimes even to undetectable levels.

If they stay elevated or start rising again, that tells us there may still be some cancer somewhere, and we’ll do further imaging to investigate.

In cases where medullary thyroid cancer spreads or comes back, there are newer treatments available, including targeted therapies—especially for patients with RET mutations. These aren't first-line treatments, but they can be helpful if the cancer isn’t fully controlled by surgery.

Let’s discuss the prognosis. Let’s compare the most common type of thyroid cancer, papillary thyroid cancer. Papillary thyroid cancer has an excellent outlook. The 10-year overall survival rate is approximately 97%, with even higher rates for low-risk patients .

In contrast, medullary thyroid cancer has a more variable prognosis. Patients with MTC confined to the thyroid gland have a 10-year survival rate of about 95.6%. However, if the cancer has spread to regional lymph nodes, the 10-year survival drops to 75.5%, and for those with distant metastases at diagnosis, it decreases further to 40% .

This comparison highlights the importance of early detection and complete surgical removal in improving outcomes for MTC patients.

Let me summarize a few key points:

Medullary thyroid cancer is rare and arises from C cells, not the usual thyroid cells
It makes calcitonin, which we use as a tumor marker to monitor the disease
Genetic testing for RET mutations is essential and may guide treatment for you and your family
Surgery is the main treatment, and getting the initial surgery done right is crucial
We use a neck ultrasound in clinic to guide the correct extent of surgery—often total thyroidectomy with central and possibly lateral neck dissection
After surgery, we track calcitonin and CEA levels to look for signs of recurrence
And if needed, there are targeted treatments for advanced cases

At UCLA, we have a dedicated endocrine surgery team that works closely with endocrinologists, genetic counselors, and oncologists to provide comprehensive care for patients with medullary thyroid cancer.

If you’d like to learn more or schedule a consultation, visit us at endocrinesurgery.ucla.edu, or give us a call at 310-267-7838. We’re here to help.

Thanks for watching—I’m Dr. James Wu. Take care, and I’ll see you next time.