All About Hürthle Cell Carcinoma

Carolyn Vachani, RN, MSN, AOCN and Kolin Hoff, MD
Updated by: Karen Arnold-Korzeniowski, BSN RN
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: May 30, 2013

What is the thyroid?

The thyroid gland is located on the anterior aspect (front) of the neck. It can be felt just below the thyroid cartilage, or "Adam's apple". It is a butterfly shaped organ that stretches across the middle of the neck just below the thyroid cartilage, with its "wings" spreading towards the head, on either side of the thyroid cartilage. These "wings" are called the lobes of the thyroid, with the middle section being called the isthmus. As an endocrine gland, the thyroid gland produces, stores, and secretes the thyroid hormones thyroxine (T4) and triiodothyronine (T3) into the bloodstream. The thyroid does this as a response to a hormone produced by the pituitary gland, called thyroid stimulating hormone, or TSH. When the thyroid gland is "turned on" by TSH, it increases its uptake of iodine, which is required to make thyroid hormone. The principal cells of the thyroid are called follicular cells and are mainly responsible for the production and secretion of thyroid hormones. Thyroid hormone plays an important role in controlling our metabolic rate. Many functions such as body temperature and heart rate are regulated by thyroid hormone. Too much thyroid hormone in your system is called hyperthyroidism, while too little is called hypothyroidism. An imbalance of thyroid hormone may cause serious problems if not properly treated.

What is Hürthle Cell Carcinoma?

Hürthle Cell Carcinoma is a type of thyroid cancer. It is estimated that there will be 64,300 new cases of thyroid cancer diagnosed in the US in 2016. The four major histopathologic types of thyroid cancer are papillary carcinoma, follicular carcinoma, medullary carcinoma and undifferentiated. Hürthle cell carcinoma is a type of follicular carcinoma and accounts for only 3% of all thyroid cancers. Researchers believe that its behavior is similar to follicular cell carcinoma, though it does tend to be more aggressive. Given how rare this tumor is, there are a limited number of reported cases and have been no clinical trials to determine the best treatment.

Hürthle cell cancer has a high incidence of metastases compared with other thyroid cancers. Hürthle cell cancer may metastasize to lymph nodes in the neck but follicular cancer does not; both hurthle cell and follicular cancers may spread by invasion into blood vessels, which may give rise to metastases outside of the neck. The likelihood of metastasis can be predicted by the pathology at the time of surgery; Hürthle cell cancers that are small and show no sign of invasion into blood vessels or lymph nodes are very unlikely to spread. Survival rates vary greatly in the published studies, depending on the characteristics of the individual patient, such as age and the invasiveness of the tumor, so it is difficult to generalize a long term prognosis. These tumors are most common between 50 and 60 years of age, but have been reported from age 20 to 85 years old. These tumors are also more common in women than men and it affects the Caucasian race at a higher rate than other races.

What causes Hürthle cell carcinoma?

It is not clear what causes Hürthle cell carcinoma specifically. Known risks of developing a Hürthle cell carcinoma are a history of external beam radiation to the head and/or neck, iodide deficiency, genetic mutations, and a family history of thyroid cancer.

How can I prevent Hürthle cell carcinoma?

As most cases of Hürthle cell carcinoma are not associated with any risk factors, there is usually no method to prevent its development. Careful examination of the thyroid and consideration of screening for patients at high risk could be considered, though general prevention is not possible. In addition, it is important that the thyroid is shielded in children who undergo diagnostic X-ray procedures, such as dental X-rays. If you have a family history of thyroid cancer, be sure to notify your primary care provider.

What screening tests are available?

The early detection of thyroid cancers is generally through careful visual and physical examination of the neck. Palpation of the neck will detect many clinically significant thyroid cancers, which is part of a routine physical exam. In addition, the thyroid gland is included on many radiology studies performed to evaluate other concerns, such as CT scans of the lungs and cervical spine. All patients suspected to have thyroid nodules, either from physical examination or from another radiology study, should have a thyroid ultrasound performed to take a picture of the thyroid. Thyroid ultrasound uses sound waves to image the thyroid gland and surrounding structures. The ultrasound appearance of the nodule can help healthcare providers determine if a fine-needle aspiration biopsy is required to further evaluate the nodule.

What are the signs of Hürthle cell carcinoma?

The most common physical sign of a Hürthle cell carcinoma is a palpable neck mass. Other signs include a hoarse voice if the vocal cords are involved, compression and deviation of the trachea, superior mediastinal syndrome which can cause facial swelling and dilated veins, and enlarged lymph nodes. Most patients with Hürthle cell carcinoma are euthyroid, meaning that the thyroid is functioning appropriately, which would not cause any concerning symptoms.

How is it diagnosed?

Once a thyroid nodule is found, the next steps are designed to determine if the nodule represents a benign growth or malignant tumor. A careful physical exam should be done by a healthcare provider, with attention to the examination of the neck to evaluate for enlarged lymph nodes. The workup may also include having blood drawn to check the function of your thyroid. Keep in mind though that you can have a properly functioning thyroid gland and be diagnosed with Hürthle cell carcinoma. Your provider may order imaging of your thyroid including an ultrasound, a thyroid uptake and scan (This scan is a nuclear medicine study using radioactive iodine. Functioning thyroid tissue takes up iodine to produce normal thyroid hormones. Therefore, the small amount of radioactive iodine given will be taken up by those areas of the thyroid that are producing thyroid hormone and then "seen" on the scan), a CT or MRI of the neck, and if your provider suspects that the carcinoma has metastasized her or she may suggest a PET scan.

Unlike many cancers, Hürthle cell cannot be definitively diagnosed with a fine needle aspiration (biopsy). While the biopsy may be suggestive of a tumor that may or may not be cancer, called a Hürthle cell neoplasm, the large majority of these will be found to be benign (called a Hürthle cell adenoma). The only way to confirm the diagnosis of cancer is by identifying capsular or vascular invasion (that is, invasive growth that is seen with cancer). This can only be determined after the nodule is surgically removed and examined by a pathologist in the laboratory. Clinicians are currently working to be able to test the cells removed through a fine needle aspiration and to determine through genetic testing if the mass is benign or malignant. As this technique continues to improve the need for surgery to confirm diagnosis will change.

Once there is a diagnosis of a Hürthle cell neoplasm, surgery to remove the affected thyroid lobe is typically the next step to clarify the diagnosis. Only 15-30% of patients will receive a diagnosis of carcinoma after surgery, with the remainder finding the nodule was benign.

How is it staged?

The staging of a cancer describes how much it has grown before the diagnosis is made. Staging documents the extent of disease. There is no specific staging system used for Hürthle cell carcinoma, but the TNM (tumor, node, metastases) system is the most commonly used staging system. Most classification systems used in this type of cancer take into account factors such as tumor size, patient age, presence of metastases, and major capsular invasion. Below is the commonly used TNM staging for papillary and follicular thyroid cancer.

TNM Staging System for Papillary and Follicular Thyroid Carcinoma

Stage

Age (less than 45)

Age (greater than 45)

1

Any T, any N, M0

T1, N0,M0

2

Any T, any N, M1

T2, T3, N0, M0

3

T4 or N1, M0

4

Any T, any N, M1

Complete thyroid cancer staging available in the article "All About Thyroid Cancer".

How is Hürthle cell carcinoma treated?

Surgery remains the primary treatment for Hürthle cell carcinoma. However, other treatments such as radioactive iodine and radiation may be used alone or in combination with surgery.

Surgery

The main treatment of Hürthle cell carcinoma is surgery, but there is some controversy as to how extensive a surgery is required, given that some tumors will behave aggressively, while others do not. The initial size of the nodule and the patient’s age and general health may help decide on the extent of the first surgery. In some cases, the entire thyroid gland is removed (total thyroidectomy) once the diagnosis is confirmed, along with any enlarged lymph nodes. Detection of cancer in any lymph nodes may lead to a more extensive lymph node dissection. Some experts feel total thyroidectomy is the best procedure because it allows follow up tests to be more effective, as residual thyroid tissue can affect these.

Radioactive Iodine

Radioactive iodine is a useful nonsurgical treatment for many types of thyroid cancers, but Hürthle cell cancer is only treatable by radioactive iodine in a rather small number of cases. A dose of radioactive iodine may be given to destroy the remaining normal thyroid tissue after surgery. The iodine is taken up into the cell and the radiation within the radioactive iodine itself is released locally, delivering a lethal dose of radiation to these cells. This treatment works well because normal thyroid cells and some thyroid cancer cells preferentially absorb and retain iodine, so other tissues are rarely affected. However, for the first few days after treatment with RAI, patients emit radiation and should avoid close contact with others. This helps to make the follow up testing for recurrence more sensitive and may also show if the tumor is able to be treated by radioactive iodine.

Radiation Therapy

In Hürthle cell carcinoma, radiation therapy is used to relieve symptoms of metastases, control recurrent tumors and to prevent recurrence. It is only indicated in patients in whom complete surgical removal is not possible. Radiation comes in the form of high energy x-rays, similar to those used for diagnostic x-rays, but they are of a much higher energy. The high energy of x-rays in radiation therapy results in damage to the DNA of cells. Cancer cells divide faster than healthy cells, and so their DNA is more likely to be damaged than normal cells. Additionally, cancer cells are generally less able to repair damaged DNA than normal cells are, so cancer cells are killed more easily by radiation than normal cells.

Clinical Trials

There are clinical research trials for most types of cancer, and every stage of the disease. Clinical trials are designed to determine the value of specific treatments. Trials are often designed to treat a certain stage of cancer, either as the first form of treatment offered, or as an option for treatment after other treatments have failed to work. They can be used to evaluate medications or treatments to prevent cancer, detect it earlier, or help manage side effects. Clinical trials are extremely important in furthering our knowledge of this disease. It is through clinical trials that we know what we do today. Talk to your provider about participating in clinical trials in your area. You can also explore currently open clinical trials using the OncoLink Clinical Trials Matching Service.

Follow-up Care and Survivorship

People facing a diagnosis of Hürthle cell carcinoma require a multidisciplinary team of doctors, including an endocrinologist, head and neck surgeon or endocrine surgeon, nuclear medicine physician, pathologist and, in a few cases, a radiation oncologist. Finding an experienced team is important in treating this rare cancer. After surgery, patients will require thyroid hormone supplementation and monitoring for life. Monitoring for tumor recurrence is done with ultrasound, measurement of thyroglobulin levels (blood test), and in some cases iodine 131 total body scanning. Other radiology exams, including PET scan, CT or MRI imaging, may be used in cases where iodine-131 uptake is not present. It is important to follow your provider’s follow-up recommendations and to speak with your team regarding any recurrent or new symptoms you are experiencing as they could be related to your treatment or recurrence.

Fear of recurrence, financial impact of cancer treatment, employment issues and coping strategies are common emotional and practical issues experienced by thyroid cancer survivors. Your healthcare team can identify resources for support and management of these practical and emotional challenges faced during and after cancer.

Cancer survivorship is a relatively new focus of oncology care. With some 15 million cancer survivors in the US alone, there is a need to help patients transition from active treatment to survivorship. What happens next, how do you get back to normal, what should you know and do to live healthy going forward? A survivorship care plan can be a first step in educating yourself about navigating life after cancer and helping you communicate knowledgeably with your healthcare providers. Create a survivorship care plan today on OncoLink.

Resources for More Information

ThyCa: Thyroid Cancer Survivors’ Association
www.thyca.org
Provides education and support for people with thyroid cancer as well as funds research into the disease.

Light of Life Foundation
www.lightoflifefoundation.org
A non-profit organization which provides education and support to people with thyroid cancer and the public.

Endocrine Web
www.endocrineweb.com/conditions/thyroid-cancer
Provides education about various endocrine conditions, including thyroid cancers.

REACT Thyroid Foundation
www.reactthyroidfoundation.org/
An advocacy organization dedicated to supporting research for thyroid cancer treatments.

References

American Cancer Society. Thyroid Cancer. 2016. Found at: http://www.cancer.org/cancer/thyroidcancer

Aytug S et al. Hurthle Cell Carcinoma. Medscape. 2015. Found at: http://emedicine.medscape.com/article/279462

Goffreddo P et al. Hurthle Cell Carcinoma. Cancer. 2012. 119(3):504-511.

PDQ Cancer Information Summaries. Thyroid Cancer Treatment. 2016. Found at: http://www.ncbi.nlm.nih.gov/books/NBK65719/

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