Interviewer: Thyroid Cancer, what is it, what causes it, what are the signs, and what can you do about it? That's next on The Scope.
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Interviewer: Dr. Marcus Monroe is a head and neck cancer expert at University of Utah Health Care. Today, it's thyroid cancer. First of all, let's just start out with, what is your thyroid and then we'll get to what is thyroid cancer.
Dr. Monroe: So your thyroid is an endocrine gland. It's a gland that's located in the neck, just above the collar bones. It's a butterfly shaped gland and it crosses over your windpipe. Its main functions are actually quite broad. It is involved in regulating a variety of bodily functions, including blood pressure, heart rate, body temperature, energy use, metabolism. In a very basic way, your thyroid gland can be thought of as your body's thermostat.
Interviewer: And then what causes... what is thyroid cancer? Other than cancer of the thyroid.
Dr. Monroe: Yes, so thyroid cancer is actually a group of cancers. The most common types are termed well-differentiated thyroid cancer, include papillary thyroid cancer, follicular cancer, and these account for over 95% of all thyroid cancers. There are rare, inherited types of thyroid cancer called medullary thyroid cancer and then some rare aggressive variants called anaplastic thyroid cancer.
But in general, when most people speak of thyroid cancer, they're most commonly referring to those most common types of follicular and papillary thyroid cancer. Something we've demonstrated in research that is that is done here at University of Utah, demonstrating in small but increased risk of even these well differentiated thyroid cancers in family members of patients with thyroid cancer. And that's been known before, that there is probably a family link. For the medullary thyroid cancer, there is a very clear genetic component associated with mutations in the RET gene, so that's a little bit different entity but also has a very strong genetic link.
Interviewer: And, as a result of that stronger genetic link, if you know that that's in your family then you should be a little bit more aware of that, I suppose?
Dr. Monroe: Yeah, it's something to be aware of.
Interviewer: So what else causes it? There can be a genetic component, what else?
Dr. Monroe: The majority of patients we know of no specific genetic component. The number of environmental exposures that have been associated with thyroid cancer are actually pretty few. The one that has really been conclusively demonstrated is the previous exposure to radiation, and we know that from some of the follow-up studies that have been done in areas that have had nuclear fallout, like the Chernobyl region, have seen vastly increased rates of thyroid cancer.
Interestingly here in Utah, there have been studies done that have demonstrated higher rates of thyroid cancer, particularly in areas that have nuclear fallout from the nuclear testing that was done in Nevada in the 1950s and '60s.
Other risk factors for thyroid cancer that aren't quite as well established include female gender, so we know that thyroid cancer is more common in females and is thought to potentially be related to some hormones, but that hasn't really been worked out. And we also have a link with obesity. We see an increase in thyroid cancer with an increase in obesity, although these links are not as strongly linked as the one with radiation.
Interviewer: What are some of the signs? What am I looking for? How do I know that I might need to Google something or go to my doctor?
Dr. Monroe: Yeah, so thyroid cancer is a little unique in that the vast majority of patients are asymptomatic and have thyroid nodules discovered either on a routine exam for some other condition or an imaging studies performed for a completely unrelated diagnosis. Specific signs of thyroid cancer can include a lump in the neck, changes in voice or swallowing, or rarely, coughing up blood. But the vast majority of patients are actually asymptomatic at the time of diagnosis.
Interviewer: So what should somebody do if their physician had done some other tests and discovered that they actually do have a thyroid nodule?
Dr. Monroe: The first thing that's important to realize is that thyroid nodules are incredibly common. They increase with age and, in fact, if you look with sensitive measures like ultrasound, over 50% of people will have thyroid nodules by the age of 50 or 60. So an incredibly common condition.
Interviewer: So it doesn't mean cancer?
Dr. Monroe: It does not mean cancer. In fact, the risk of cancer in any individual with thyroid nodules is actually quite low, somewhere in the range of 5 to 10%.
Interviewer: So that's kind of nice to hear.
Dr. Monroe: Yes. So I think it's nice. Now, as of right now we don't have great ways of differentiating them other than characteristics on the ultrasound and by biopsy. So for patients who are diagnosed with a thyroid nodule most will be referred to an endocrinologist or a surgeon who specializes in thyroid cancer for evaluation of the characteristics of the nodule as well as their thyroid gland function.
The testing typically begins with measurement, a blood test to measure your thyroid function, and then, in most cases then an ultrasound. There are very specific criteria that have been laid out that demonstrate which nodules harbor an increased risk of thyroid cancer and which nodules should be biopsied, so not all nodules need to be biopsied. Those that are larger in size or have worrisome characteristics by ultrasound, the next step is to then attain a fine needle aspiration, which is a small biopsy with a needle that can be done in clinic.
Interviewer: So a nodule doesn't necessarily mean cancer. If it is diagnosed and it is determined that there is cancer going on, what would be the steps after that? What's the treatment look like?
Dr. Monroe: The treatment for thyroid cancer typically involves surgery. Depending on the size and location of the cancer within the thyroid, that may involve removing either half or the entire thyroid gland. Occasionally, removal of regional lymph nodes is required if the cancer has spread to the lymph nodes or if there's a particularly high risk of cancer spreading to the lymph nodes.
Once surgery is over, a select group of patients that are at higher risk may need additional therapies. The most common of those is radioactive iodine, which is a pill that can be taken afterwards that has radiation tagged to an iodine molecule. Now the thyroid is a little bit unique in that it takes up this iodine and can concentrate the radiation to kill any remaining thyroid cancer. That's really only used in patients that are deemed higher risk for the cancer coming back afterwards.
Interviewer: And what's life look like after thyroid cancer treatment?
Dr. Monroe: The good news is that if we look at all the different shades of thyroid cancers, the most common thyroid cancer rates of survival are excellent. Survival rates at 5 and 10 years are well above 95%. Survival is great. The unfortunate thing is that we don't really have a lot of data on what sort of health problems people have after treatment, so that remains an unanswered question. But in the vast majority of cases, patients are able to go back to their normal life and function normally.
Interviewer: So for the most part, quality of life after the treatment
Dr. Monroe: Yeah, as far as I know--
Interviewer: Is normal, unaffected?
Dr. Monroe: Yeah.
Interviewer: Any final thoughts? Anything you wish I would have asked or anything you feel compelled to say?
Dr. Monroe: I think the important thing to realize is that, because survival is so good, nodules are so common, thyroid cancer is not something we recommend screening for. In fact, if we look at countries that have started screening for thyroid cancer, we see some really interesting findings. So if we look at South Korea, for instance, they started a screening program for cancers in the '90s and, as part of that, many hospitals offer ultrasound based thyroid screening. And what they have found is that thyroid cancer has now become the most common malignancy in that country, far surpassing any other cancers.
The interesting thing about it is the number of people who die of thyroid cancer has remained unchanged. So I think it's really important when we talk about screening for these cancers is that to realize that one, these cancers are actually very common, and two, they are unlikely to affect a person significantly during their lifetime. There's general though that, in many cases, the risks of screening and all the testing and biopsies that need to go into finding these nodules probably outweighs any benefit.
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