Has My Thyroid Cancer Spread?

Hi there, I’m Dr. Michael Yeh, a surgeon at UCLA Health, here to answer the question: How do you know if your thyroid cancer has spread?

This is a question we receive frequently. Thyroid cancer can spread in several ways. The most common form is spread to nearby lymph nodes in the neck, which is generally not a major concern because those are usually straightforward to remove during surgery.

Another potential route of spread is direct invasion into neighboring structures—such as the airway or esophagus. A third, more serious way it can spread is through the bloodstream to distant sites, such as the lungs or bones. Fortunately, spread of thyroid cancer beyond the neck is very rare—occurring in fewer than 5% of cases.

As you may know from our other videos, the most common type of thyroid cancer is papillary thyroid cancer, a slow-growing form that accounts for more than 90% of thyroid cancers diagnosed today. Most of these stay within the thyroid or may involve nearby lymph nodes.

So, how do you know if your thyroid cancer has spread?

Often, we don’t know immediately. Patients typically want answers as soon as they are diagnosed, but the full picture unfolds over time. So let’s go through the individual steps where we gain information about a given person’s cancer.

Step 1: Biopsy Most patients start with a needle biopsy that confirms the presence of abnormal cells.
Step 2: Imaging An ultrasound, or sometimes a CT scan, helps us see whether the cancer has spread to nearby lymph nodes or invaded adjacent organs.
Step 3: Surgery During surgery, we learn more—such as whether a complete removal was possible and if we achieved clear margins (no cancer at the edges of the removed tissue).
Step 4: Pathology Report About a week after surgery, a pathology report provides even more information: the tumor subtype, aggressiveness, margin status, and whether lymph nodes or nearby organs were involved.

In 90–95% of cases, we find that the cancer has not spread outside of the neck by this stage.

What happens next?

Roughly 20–25% of patients receive radioactive iodine as follow-up treatment, if their thyroid cancers are considered intermediate or high risk for recurrence.. This helps destroy any microscopic remnants of thyroid tissue, whether normal or cancerous. After this treatment, we do a whole-body scan to detect any spread beyond the neck.

We also begin measuring thyroglobulin levels, a tumor marker useful after a total thyroidectomy. Since thyroglobulin is produced by normal thyroid cells and most types of thyroid cancer cells, we want that level to be as close to zero as possible.

Here’s a rough guide to interpreting thyroglobulin levels:

Less than 1.0: Generally very reassuring.
1–10: Might suggest some residual cancer cells, possibly in a lymph node.
10–99: Raises suspicion for possible spread to the lungs.
100 or more: May indicate spread to bone or other distant sites.

Even if your levels are elevated, it doesn’t mean a poor outcome. Most people with detectable thyroglobulin levels still live long, healthy lives.

In Summary

Statistically, it is unlikely that your thyroid cancer has spread. But over the first few months of diagnosis, treatment, and follow-up, we gradually build a clearer picture of your cancer.

I often tell my patients: At first, your future looks like a blurry image that comes into focus over time. By the one-year mark, we typically have a very good understanding of your disease status and a clear vision of your long-term prognosis.

Roughly 95% of our patients are disease-free at one year and go on to live full, healthy lives, thankfully without having to see us doctors too often. For the remaining 5%—those with known recurrence or considered high-risk for recurrence—we stay vigilant and offer continued surveillance and further treatment as needed to ensure the best possible outcomes.

I hope this answered your question. Once again, I’m Dr. Michael Yeh from UCLA Health, and thank you for watching.