Thyroid cancer

 “Suspicious” thyroid nodules and thyroid cancer:
Suspicious thyroid nodules are usually identified by ultrasound imaging features that are associated with an increased risk of thyroid cancer. These features include an appearance darker than the surrounding thyroid (hypoechogenicity), solid composition (as opposed to being fluid-filled like a cyst), tiny calcified areas within the solid parts of the nodule (microcalcifications), irregular borders (versus smooth borders), invasion of nearby structures (e.g., blood vessels, muscles), and a shape that is taller-than-wide. Additional features that raise concern for thyroid cancer include rapid growth of the nodule and abnormal or enlarged lymph nodes in the neck near the thyroid.

How are thyroid cancers detected?

The majority of thyroid nodules are discovered by accident during imaging for other medical conditions, including ultrasound, neck or chest CT scan, and PET scan.
Some thyroid cancers are detected because the cancerous growth may cause compressive or cosmetic symptoms of the neck prompting the patient to seek medical care. Such symptoms may include hoarseness, difficulty swallowing, discomfort with lying down, or a rapidly enlarging mass in the neck.
Larger thyroid nodules can often be felt during physical examination but it is important to know that most thyroid nodules cannot be felt either by you or your doctor, and even these small nodules are just as likely to be cancer. Using ultrasound to analyze the appearance and features of thyroid nodules is therefore one of the most important initial tests you can have.

What is the evaluation?

The evaluation of a thyroid nodule includes a history and physical examination, measurement of thyroid stimulating hormone (TSH) level in the blood, and neck ultrasound. Neck ultrasound helps demonstrate the number and size of nodules in the thyroid, the likelihood that the nodule may be cancer, and whether abnormal lymph nodes are present in the neck near the thyroid. Your doctor may also recommend a CT scan or MRI of the neck as part of the evaluation. Those with voice changes due to a thyroid nodule may also require evaluation of the vocal cords. For most thyroid cancers, scanning the entire body is not necessary before surgical treatment. Exceptions include cancer subtypes such as medullary or anaplastic thyroid cancer, or if there are signs that the cancer is in an advanced stage.

What are the non-surgical options for thyroid cancer?

Non-surgical options for thyroid cancer include active surveillance and minimally invasive therapies like radiofrequency ablation (RFA). Active surveillance involves monitoring the cancer with neck ultrasound, which is performed once or twice annually. For patients under active surveillance, surgery will be recommended if the cancer grows in size if abnormal lymph nodes are detected, or if the patient prefers surgical treatment.
The most common minimally invasive therapy for non-surgical treatment of thyroid cancer is radiofrequency ablation which is a needle-based procedure usually done without general anesthesia. The cancer is not removed but is instead destroyed using heat energy. Recovery is typically much quicker than with surgery, and the patient is much less likely to require lifelong thyroid hormone supplementation—however, continued surveillance after RFA is required, much like with active surveillance.

Tumor and imaging features that would make a thyroid cancer eligible for non-surgical treatment, including active

surveillance or RFA, include the following:A single thyroid cancer no greater than 1.5 centimeters (about ¾ inches) in size

Location within the thyroid gland away from critical structures

Well-defined tumor edges on ultrasound

No involvement of surrounding structures

No suspicious lymph nodes or other evidence of cancer spreading outside the thyroid

It is also important to consider the experience of the physician and the medical center. Patient characteristics are also key: patients whose age or other health conditions make surgery unsafe may be better treated with non-surgical approaches. Finally, patient preference is always a key factor to consider.

What about cancerous lymph nodes?

After a thyroidectomy for thyroid cancer, cancer may recur in the lymph nodes that are in the neck around the thyroid bed. When this occurs, surgical removal of the lymph nodes is the standard of care. In very select cases a minimally invasive treatment like radiofrequency ablation may also be an option allowing you to avoid surgery. In general, the best candidates are patients who only have 1 or very few malignant lymph nodes and those who have had multiple prior surgeries in the same area of the neck which sometimes complicates additional surgery in the same location. A minimally invasive therapy may also be considered for those who are not physically fit enough for surgery.
Importantly, treatment with a minimally invasive therapy can only target cancerous lymph nodes that are known at the time of the treatment.  Other lymph nodes in the area that may also contain microscopic cancer cells will not be treated and some studies show that a small number of treated patients will develop recurrent cancer in lymph nodes nearby or elsewhere in the neck within 5 years. For this reason, surgery to remove all lymph nodes in the region of a cancerous lymph node is still the approach preferred for most patients.  

Surveillance after radiofrequency ablation of thyroid cancer

Surveillance after minimally invasive treatment like radiofrequency ablation includes clinical examinations and neck, and ultrasound at regular intervals to ensure that a treated thyroid cancer does not recur.