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Understanding The New TNM Staging System for Thyroid Cancer

While thyroid cancer isn’t common in America, its incidence is on the rise, perhaps due to more effective screening procedures. It’s also a cancer that usually responds well to treatment. In 2018, new definitions for thyroid cancer stages took effect to more accurately reflect the experience of clinicians across the country. Generally, stages of cancers define themselves by how far the disease has spread.

Cancer stages

There are five stages of cancer, though only some cancers use the Stage 0 classification. These stages are:

The TNM system

Thyroid cancer stages are usually defined using the TNM system of the American Joint Committee on Cancer. The system considers three key points. Each letter has a further value assigned to it, with higher numbers indicating a more advanced level of cancer. The combination of these values determines the progress, or stage, of the overall thyroid cancer. The letters in TNM represent:

Each of these letters has a range of values to indicate the state of advancement for that component. T has 10 qualifiers, N has five, and M has three. The combination of these qualifiers plus the type of tumor, and sometimes the age of the patient, guide the stage definition of thyroid cancer.

Types of thyroid cancer

Thyroid cancers first fall into differentiated or undifferentiated types. Papillary and follicular forms comprise the differentiated thyroid cancers. These are more common and usually carry a good prognosis.

Anaplastic thyroid cancer is synonymous with undifferentiated thyroid cancer. It’s rare and always classed as stage IV. Medullary thyroid cancer falls outside of differentiated and undifferentiated definitions, originating in thyroid C cells.

Clinical versus pathologic stages

When a patient has had surgery that examines tissue surrounding the tumor, observations of the tumor are used to rank the TNM values of the thyroid cancer. Ranking a cancer’s progress through surgery creates a pathologic stage for the tumor. When surgical observation isn’t possible or hasn’t been done, a clinical stage value is estimated and might not be as accurate as pathologic staging.

Staging any cancer can be complex, and it’s certainly the case with thyroid cancers. The new 2018 TNM guidelines may place some patients at a lower stage than previously, but it may not represent a form of the cancer that’s less serious or less aggressive. Any case of thyroid cancer needs close monitoring, even if it’s differentiated and given a low stage number.

The ear, nose, and throat specialists at Lawrence Otolaryngology Associates are thyroid experts, ideal partners through diagnosis and treatment of thyroid cancer. Contact the most convenient office by phone if you or a loved one is dealing with this disease.

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