Why tests put a mind at ease
Thyroid nodules are common, but thyroid cancer is rare
WHO’S AT RISK
Thyroid nodules aren’t exactly a household word, but upwards of 60-70% of the general public have at least one nodule if they are examined closely enough. “Thyroid nodules are abnormal growths or lumps that form in the thyroid, and they are very very common. Thankfully, the vast majority are benign — thus posing no risk and requiring no treatment,” says Urken. “However, the risk is that some nodules may harbor a malignancy — which is why we want to detect nodules early and evaluate them.”
There are a number of ways to detect thyroid nodules. “In some cases we find nodules on the basis of a physical exam that simply involves palpating the thyroid gland, which sits at the base of the neck,” says Urken. “Sometimes we have the patient swallow, which causes the surrounding muscles to contract and raises the thyroid gland into a higher position in the neck. And ultrasounds, CT scans, and other medical imaging techniques allow us to diagnose many more nodules than we did in the past.”
Once thyroid nodules are detected, the question is whether they are harmless or a form of thyroid cancer. “The decision to biopsy is partly based on the features of the nodule, the ultrasound criteria, and the size of the nodule,” says Urken. “We can use the ultrasound to look for any suspicious features — whether there appear to be calcium deposits, or irregular margins. The presence or absence of these features can help us to determine whether it’s appropriate to do a biopsy.”
Fine needle biopsies are the gold standard for determining whether nodules are malignant or benign. “Using ultrasound guided placement, we place the needle into the thyroid nodule and remove a tissue sample,” says Urken. “Then we look at the sample cells under the microscope to determine whether the nodule is cancerous or not.”
Most cancerous thyroid nodules are randomly occurring, but doctors have identified two contributing factors. “One risk factor is being exposed to ionizing radiation in early life — for instance, the Russian population exposed to fallout from the Chernobyl disaster,” says Urken. “The second is genetics: some thyroid cancers can cluster in families, though the vast majority are sporadic.”
SIGNS AND SYMPTOMS
Thyroid nodules often cause no symptoms until they reach a certain size. “The majority of people are asymptomatic, have normal thyroid function, and are surprised to learn that they have a nodule,” says Urken. “Only when the nodule becomes so large that it distorts the airway or the esophagus might patients notice symptoms like breathing problems or voice changes.”
TRADITIONAL TREATMENT
The first step after diagnosis is to evaluate whether the nodules raise any red flags. “The workup of a thyroid nodule usually begins with characterizing it by ultrasound — then the doctor puts together a variety of metrics to make a determination about whether or not the nodule needs to be biopsied,” says Urken. “We factor in history of radiation exposure, family history, presence of suspicious lymph nodes, any other imaging results.”
The American Thyroid Association’s most recent guidelines recommend that nodules should not be biopsied unless they reach 1 centimeter in size, unless there are extenuating circumstances, like family history.
Doctors rank biopsy results on a 6-point scale, with 6 being the number assigned to malignancy. “Once we get the biopsy back, we do the cytology classification, and then we act on the results based on risk,” says Urken. “Generally, benign nodules don’t require any treatment, unless they are so large that they are causing cosmetic concerns or trouble swallowing, breathing, or talking.”
The treatment options for malignant thyroid nodules have changed. “We used to recommend that all cancerous thyroid nodules be treated surgically, and the vast majority still are,” says Urken. “Because we now know that some early stage cancers may never develop to the point where they pose a threat, some patients may opt for active surveillance — a term we use for regularly monitoring patients in a structured way with follow-up ultrasounds.” An increase in size of over 2 millimeters a year, the development of suspicious lymph nodes, or the development of vocal cord paralysis would all be signs that the cancer should be removed.
The surgical treatment for thyroid nodules, like other thyroid cancers, is called thyroidectomy. “This is the removal of part or the entirety of the thyroid gland,” says Urken. “Patients who have the whole thyroid removed require thyroid hormone replacement — for most people, it’s a very uncomplicated replacement that allows them to carry on their normal life.”
RESE ARCH BREAKTHROUGHS
Women are three times more likely to develop thyroid cancer than men. “It’s a significant disparity — it’s something related to the presence of female hormones,” says Urken. “Figuring out why women’s risk is so much higher is a field of active research.”
QUESTIONS FOR YOUR DOCTOR
When you go in for a checkup, be proactive by asking, “Can you do a thyroid evaluation?” If your health care provider does detect a nodule, ask, “Could you refer me to an office experienced in performing thyroid nodule ultrasounds and in reading the results?” If anyone else in your family has also been diagnosed with thyroid cancer, the next question is “What is the appropriate workup to check my family members for thyroid cancer?” “Thyroid nodules are incredibly prevalent, and this is one of those circumstances where early detection can make a huge difference in the outcome,” says Urken. “The good news is that the majority of nodules are benign and don’t require surgical intervention — we just want to catch the ones that do.”