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Scott Webb (Host): I'm Scott Webb. And I'm joined today by endocrinologist Dr. Shruti Dave. And she's here to discuss the different types of thyroid cancer and more.

Dr. Dave, it's nice to have you here today. We're going to talk about thyroid cancer awareness. I know that September was Thyroid Cancer Awareness Month, so it's a great time to have you on, great time to benefit from your expertise, and maybe let's just start there, the most obvious one, right? Like, what are the four main types of thyroid cancer?

Dr. Shruti Dave: So, thyroid cancer, the four main types are papillary thyroid cancer, follicular thyroid cancer, oncocytic carcinoma of thyroid, and then invasive encapsulated follicular variant papillary thyroid cancer. These are 90% of thyroid cancers that are considered well-differentiated thyroid cancers. Then, there are some other rare types that arise from follicular cells and non-follicular cells that are less important because they are very, very rare.

Host: Right. What you gave us there covers like 90% basically.

Dr. Shruti Dave: Yeah.

Host: So, I want to have you talk about the frequency, right? I know papillary is maybe the most common, but talk to us about the different types and how common they are.

Dr. Shruti Dave: Yes. So, papillary thyroid cancer, about 85% of thyroid cancers we find in iodine sufficient areas are going to be papillary thyroid cancer. Twelve percent will be follicular thyroid cancer, and then the remaining types are obviously much less common. The 5 or so percent comprises them all. The really aggressive one, anaplastic follicular cell-derived thyroid cancer, which I didn't include in the four, is like one to two per million per year.

So, not that they are not important, but they are just so uncommon. And so, common one is papillary thyroid cancer, follicular thyroid cancer. Most of the treatments and such are common to papillary and follicular thyroid cancers. And so, they're lumped up together as well-differentiated thyroid cancers.

Host: Sure. And I wanted to ask you about risk factors, be it age, you know, genetics, family history. Who's most likely to develop thyroid cancer and perhaps why?

Dr. Shruti Dave: Radiation exposure is a known risk factor. So, radiation exposure as in being around nuclear disasters or as a child receiving radiation treatments, for example. And in very old days, nowadays we don't do this anymore, but in old days, acne, tonsil enlargement used to be treated with certain radioisotopes.

And so, once we learned that those can lead to increased risk, the use of them was stopped more than 50, I believe, 60 years ago now. So, they've become less important factors. Family history does play a role. There is higher likelihood of developing cancer if you have a first-degree relative with thyroid cancer. The precise correlation, so, you know, data regarding it will vary. But if you have a parent or a sibling with thyroid cancer and you have thyroid nodule, we would keep that in mind when making decisions about how aggressively to evaluate it and even for treatment decisions, it matters. So, those are perhaps two important ones.

Age is a risk factor more in terms of older age group tends to have worse prognosis or a lot of times they will present with more aggressive types or more advanced stage of thyroid cancer. And then, male sex is not consistently, but somewhat correlated also with a little higher risk of having more aggressive thyroid cancer. And then, obesity is something that is still being looked at and certain environmental factors. But we don't have conclusive evidence about some of those.

Host: Right. Work is still ongoing in terms of the correlation or risk factors. How would someone know to even bring this up maybe to a primary care physician or want a referral to an expert like yourself? Like, what are maybe the signs and symptoms that might be reason for concern?

Dr. Shruti Dave: More often than not, actually, thyroid cancers will get diagnosed as incidental finding. Nobody's looking at thyroid specifically, but you're getting a sonogram of your blood vessels in the neck, or you're getting an MRI of your spine in the neck, or if you're getting CT scan of the neck or chest for some other reasons, thyroid nodule can be seen as what's called an incidental finding.

Sometimes your primary care provider on routine physical will feel your thyroid and be able to palpate either a thyroid nodule or feel that the thyroid is large, so they will then order studies. But patients can sometimes present with pressure symptoms. So, change in the voice, difficulty swallowing, and then less often with more aggressive thyroid cancers, if they invade surrounding structures or get very large, it could lead to breathing difficulty. Blood vessels can get affected, so you can get swelling of certain face, neck area, headaches. But those are uncommon presentations of thyroid cancer.

Host: Right. And as you say, a lot of times it's diagnosed or found sort of incidentally or, I don't know, accidentally. So, you're looking for something else and they say, "Oh, you know what? You might want to, right, talk to Dr. Dave about this." So then, let's talk, Dr. Dave, about the current treatment options.

Dr. Shruti Dave: Yes. So once thyroid cancer gets diagnosed, and typically diagnosis is made with something called fine needle aspiration biopsy, then the current way to approach thyroid cancer treatment once a diagnosis is made is to then assess the risks and benefits of proposed treatment. And so, treatment primarily is surgery. And then, there is some role for radioactive iodine, and in very, very handful cases, local radiation treatment or some systemic therapy, and those are more advanced.

But the first step is to evaluate is a treatment necessary, how aggressive the treatment needs to be. And the reason I say that is very small, papillary thyroid cancer that's one centimeter or less, that has very clear margins. It is not associated with any abnormal looking or abnormal-feeling lymph nodes, does not always right away need surgery.

So, there is something called active surveillance, where you would monitor potentially that small of a nodule if the patient is comfortable with it, does not have associated anxiety if the experts following it are confident about it, and so on. And at some point, then those, if they get larger or if abnormal lymph nodes develop, would proceed to surgery. So, surgery is the primary treatment.

Host: Right. Surgery's the gold standard, if you will, and sometimes surveillance is the protocol. Depends on the situation, the size, the patient, and all of that. Good stuff today. Great to benefit from your expertise. I wanted to have you maybe talk about some of the updates from the 2025 ATA guidelines, just so that we're all on the same page, if you will.

Dr. Shruti Dave: Yes. And so, one of the updates was in evaluating. So, American Thyroid Association puts out a staging structure, so to speak, that helps you evaluate risk of recurrence of thyroid cancer. And the risk categories used to be low risk, high risk, intermediate risk. There is reclassification to include two separate categories in the intermediate category, basically.

So, low intermediate has 10 to 15% risk of recurrence. Intermediate high has 16% to 30% risk of recurrence. High risk are more than 30% risk of recurrence, and low risk is less than 10% recurrence. And so, it uses size, the type of cancer, the subtype of cancer, what is the histology, if it's invaded lymph nodes, has it gone to surrounding structures, if there is metastasis to other parts of your body besides the neck.

All of that is used to make decisions regarding radioactive iodine treatment whether it is needed or not needed after surgery. And so, there is revision in that risk category. That's one of the major revision. The general push toward doing less aggressive treatment where it is appropriate. So, lower risk cancers can be treated with just lobectomy rather than total thyroidectomy. Of course, selection is made based on many factors that include ultrasound appearance, biopsy results. There are molecular marker tests that get done, although they are not routinely recommended to be tested, but there are situations where they will get done during biopsy.

So, all of those help decide, but there is more push toward doing less invasive surgery when we know this looks more like low-risk thyroid cancer, and trying to get better at finding those more aggressive or higher risk of recurrence patients and doing more aggressive surgery.

Another update is being able to evaluate patients who have not been treated with radioactive iodine treatment to assess their response to initial treatment. In the prior American Thyroid Association guidelines, that category was not clearly indicated. Now, we have data to use a blood test called thyroglobulin. It's a protein that is made by thyroid. And so, evaluating that six to twelve weeks after surgery guides your further treatment, who has already achieved excellent response, who is in the indeterminate category where risk of recurrence is 15%, 20%, who's in biochemically incomplete category where risk of recurrence is about 30%.

So then, thyroglobulin will guide. If thyroglobulin is less than 0.2%, less than 0.2 milligram while your TSH is normal, then you have achieved excellent response. Or if the thyroglobulin is less than 1 with high TSH, that's also considered excellent response if a patient has had surgery and radioactive iodine treatment.

If the patient only had surgery, there was no need to do radioactive iodine treatment, then thyroglobulin value that's less than 2.5 classifies the patient as excellent response category. So then, you can slow down on the amount of monitoring that you do. You will still follow patients with thyroglobulin measurement every one to two years, ultrasound testing of the neck every one to three years. But in the higher risk categories, you're going to do that more often. You'll maybe do thyroglobulin every six months and imaging. So, that's the other major update, and then, new TSH goals.

So, one of the other basic treatment that all patients with, or most patients I should say, with thyroid cancer will have is thyroid hormone replacement. Those that have only had part of the thyroid removed in many cases will not need treatment if they maintain normal thyroid hormone levels, which are indicated by normal TSH value. But there are some of those patients who will require thyroid hormone replacement, because TSH level rises when your body senses there is not enough thyroid hormone. And those who have had thyroid removed with or without radioactive iodine are treated with thyroid hormone. So historically, we've treated patients with high dosages of thyroid hormone for all thyroid cancer patients.

Now, there is data to support not using high dosages for those patients who have achieved excellent response or those who are in indeterminate category with 15% to 20% risk of recurrence and had low-risk cancer to start with. Those who do have higher risk of recurrence, judicious use of higher dose of thyroid medication is still recommended, but you evaluate the risk of high-dose thyroid treatment, thyroid hormone treatment, which is bone density gets lower and heart rhythm problems become more common as you treat patients with higher dosages of thyroid hormone. So, trying to be more judicious about replacement is the other area.

Percutaneous ablation treatments for small thyroid cancers that are low risk is more and more being studied and adapted in United States. It is something that's been done for some time now in Asia and Europe. And then, molecular marker testing or evaluating molecular risk group for thyroid cancer is something that's being increasingly studied and is likely to be more helpful in stratifying patients, which ones need more treatment, targeted treatments, which one will benefit from radioiodine and so on.

Host: Yeah. Well, it's great to have you on, great to benefit from your expertise, catch up, if you will, on thyroid cancer, the different types, treatment options, guidelines, and so forth. Thank you so much.

Dr. Shruti Dave: Good to be here.

Host: For more information and to get connected with one of our providers, please visit carle.org. And that wraps up this episode of Expert Insights with the Carle Foundation Hospital. I'm Scott Webb. Stay well.