Michael Bouvet, MD
Surgical advancements, particularly nerve monitoring and parathyroid imaging, have played an important role in evolving the treatment for localized thyroid cancer. However, challenges still exist as to determining whether an individual patient’s tumor warrants surgical intervention or observation.
“The positive thing about thyroid cancer is that it’s still a very curable disease type of cancer,” said Michael Bouvet, MD. “It just has to be done properly and taken care of properly. There is a greater awareness of thyroid cancer and signs and symptoms, and people need to know that there is hope for them if they have this diagnosis.”
In an interview during the 2017 OncLive®
State of the Science SummitTM
on Head and Neck Squamous Cell Carcinoma. Bouvet, professor of surgery at the University of California, San Diego, highlighted the evolving surgical options in the thyroid cancer field.
OncLive: What are the common symptoms and risk factors of thyroid cancer?
: Thyroid cancer is increasing in frequency and it often presents in younger patients. Some of the patients are as young as 20 years old and the average age of diagnosis is about 40. Oftentimes, it will just be something that the patient discovers—a little lump in their throat—or it could be discovered by their primary care physician in the office who did a neck exam and they found a little lump in the neck.
The next work-up would be an ultrasound. Patients would get an ultrasound of the thyroid, and if the nodule is bigger than 1 centimeter than it typically gets biopsied. Fortunately, most thyroid nodules are benign, but sometimes they can be cancerous. If they are cancerous, then the treatment is primarily surgery.
There are several risk factors for thyroid cancer. One is a history of radiation exposure. So, if people were around when the Chernobyl incident in Russia happened, they would have been exposed to radiation in that area of the world and could have potentially developed thyroid cancer. More recently, there was a radiation disaster in Japan—Fukushima in 2011— and that was a scare for a lot of Japanese people being exposed to radiation.
Having said that, we don’t know what causes most thyroid cancers. There are some people with a family history of thyroid cancer and, in that case, they can be at risk if they have a certain gene that they inherited.
How has biology become an important prognostic factor for thyroid cancer?
That is what we are trying to figure out with thyroid cancer. There are different types of thyroid cancer. The most common is papillary thyroid cancer and, even within the papillary subset, you get some tumors that are sort of indolent and small. Some people even say we don’t need to treat them; we can just do observation if they are small.
On the other hand, if patients get papillary thyroid cancer that has spread into the lymph nodes, they sometimes cause a lot of local problems. Patients can get hoarseness if it’s invading the current laryngeal nerve; you can get pressure sensations in the neck if it spreads to local areas, so we are trying to figure out which patients are going to develop which type of thyroid cancer.
Then, there are more rare types, such as follicular thyroid cancer and medullary thyroid cancer, that have sort of unique biologic properties. It is a wide spectrum of types of cancers. Each patient has an individual course of treatment that they take.
Is there any work that you’re involved with you would like to highlight?
I am a thyroid cancer surgeon, so every week I am operating on patients with thyroid cancer. One of the things that we are very cognizant of and are very careful of is to try to avoid complications when we do thyroid surgery. We are always evaluating new techniques. Nerve monitoring has been around for a while, but we would like to monitor the recurrent laryngeal nerves while we are doing the surgery so that we can avoid an injury to the nerves and, if they do get injured, patients can get hoarse. That is an important part of trying to prevent that complication. The nerve monitors have gotten better over time.
The other [exciting] thing that we are doing has to do with one of the potential complications during thyroid surgery: damage to the parathyroid glands. There are 4 little small parathyroid glands, which sits behind the thyroid that controls calcium. During surgery, we want to leave those parathyroid glands in the neck to make sure they have a good blood supply and that they make enough parathyroid hormones so your calcium levels stay normal.
One thing we have started to do is that, after we have taken out the thyroid, we will inject indocyanine green dye. We have a specialized fluorescence imaging system in the operating room now that can assess the perfusion, or blood flow, to the parathyroid glands. A recent study from Switzerland showed that if you have at least one parathyroid gland that is well perfused, then you don’t need to worry about the low calcium levels after surgery. Therefore, there are some newer techniques we are using to try to make thyroid cancer surgery safer for patients.
Can you comment on technological advancements in surgery over the last couple years?
We have made a lot of advancements. In fact, it is amazing to think about how far surgery has come from the days of Dr Theodor Kocher 100 years ago. Now, we have a variety of tools to help us make the surgeries safer—nerve monitoring, as I mentioned, and this parathyroid imaging.
However, we also have newer, haemostatic agents that help control bleeding, and there are ways we can dissect through thyroid tissue with special instruments. Believe it or not, some people are even doing remote access thyroid surgery through the armpit or through face lift incisions or even through the mouth; they do this in Thailand. We are only seeing the beginning of a new approach to surgery for thyroid and thyroid nodules.
What significant challenges still exist in surgery for thyroid cancer?
The real challenge is to figure out how much to treat and how much to just observe. If you have somebody with a real tiny cancer, perhaps we don’t have to rush and induce surgery right away. On the other hand, the initial operation for somebody with a larger tumor that may have spread is very important because, if the surgeon can go in and really do a good job the first time around then the patient will hopefully avoid a redo operation, which has its own risks, so we try to do a complete job.
The other thing that is a new improvement in the treatment of [patients with] thyroid cancer is preoperative staging with comprehensive ultrasound. That is being done with surgeons in the clinic, and we want to make sure which lymph nodes may be involved in the tumor before we go in there. This is so we can do a good job with our surgery and make sure that we get [all of the tumor] out. Ultrasounds have almost become an extension of the physical exam, and those ultrasound machines are just getting so good. Surgeons and endocrinologists are getting better at ultrasonography in the clinic so they can do their own needle biopsies and plan out thyroid surgery better.