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Advanced Thyroid Cancer

Determining the Stage of the Cancer

The final step before discussing treatment options is a determination of the stage of the cancer. As with all cancers of the head and neck, doctors in the U.S. use the AJCC Cancer Staging Manual (7th edition) to determine the stage based on three factors.

Factors that go into determining the stage of the cancer
T Characteristics of the main tumor mass
N Status of the lymph nodes in the neck (i.e., evidence of cancer spread)
M Status of cancer spread to parts of the body outside of the head and neck

However, staging of thyroid cancer differs from other cancers because your age at the time of your diagnosis plays a role. In fact, for papillary or follicular carcinoma, if you are under the age of 45, the highest stage of thyroid cancer you can have is stage II.

At first, you will be given a clinical stage based on all of the available information.

  • Clinical staging (cTNM) is determined from any information your doctor might have about how extensive the cancer is BEFORE starting any treatment. Stage is determined based on your doctor’s physical exam, imaging studies, laboratory work and biopsies. Classification of clinical stage is described using the lowercase prefix c (e.g., cT, cN, cM).

If there is surgical removal of the cancer as part of your treatment, a pathologist will analyze the tumor and any lymph nodes that may have been removed. You will then be assigned a pathologic stage.

  • Pathologic staging (pTNM) provides more data. Classification of pathology stage is described using the lowercase prefix p (e.g. pT, pN, pM). This may or may not differ from the clinical stage.

There are also a number of other lowercase prefixes that might be used in the staging of your cancer.

  • The subscript y (yTNM) is used to assign a cancer stage after some sort of medical, systemic or radiation treatment is given (Posttherapy or Post-Neoadjuvant Stage). It is typically combined with either a clinical or pathologic stage. For example, ycT2N0M0 indicates that after some sort of non-surgical therapy, the new clinical stage is T2N0M0.
  • The subscript r (rTNM) is used when the tumor has recurred after some period of time in which it was gone. This is called Retreatment Classification Stage. Your doctor will use all the available information to assign you a retreatment stage.

T stage: the main tumor mass

Based on a physical examination and review of any imaging, your doctor should be able to give you a T stage that falls within one of the following categories.

78_thyroid_Tstage

Tx The primary tumor cannot be assessed.
T0 There is no evidence of the primary thyroid tumor.
T1a The tumor is 1 centimeter or less and completely within the thyroid gland.
T1b The tumor is between 1 and 2 centimeters and limited to the thyroid gland.
T2 The tumor is between 2 and 4 centimeters and limited to the thyroid gland.
T3 The tumor is more than 4 centimeters and limited to the thyroid gland OR any tumor that has minimal extension outside of the thyroid gland.
T4a Moderately advanced disease: The tumor is any size but extends beyond the thyroid capsule to invade the subcutaneous tissue, larynx, trachea, esophagus or recurrent laryngeal nerve.
T4b Very advanced disease: The tumor invades the prevertebral fascia or surrounds the carotid artery or major chest vessels.

Note that all anaplastic thyroid cancers are T4 tumors (T4a if the tumor is within the thyroid gland or T4b if the carcinoma has gross extension outside the thyroid gland).

N stage: spread of cancer to the lymph nodes in the neck

Next, your doctor will use all the available information and assign you an N stage. This is based on the assessment as to whether the cancer has spread to lymph nodes in the neck.

79_thyroid_Nstages

Nx The neck lymph nodes cannot be assessed.
N0 There is no evidence of any spread to the nodes.
N1a The cancer is in level VI nodes. This includes pretracheal, paratracheal and prelaryngeal nodes.
N1b The cancer is in lymph nodes in the lateral neck (levels I to V) or retropharyngeal nodes or level II (upper mediastinum/chest).

M stage: spread of cancer outside the head and neck

Finally, based on an assessment on the entire body, you will be assigned an M stage.

M0 No evidence of distant (outside the head and neck) spread.
M1 There is evidence of spread outside of the head and neck (i.e., in the lungs, bone, brain, etc.).

Your cancer stage

After TNM staging, your doctor will assign a cancer stage based on the following chart. Staging of well-differentiated thyroid cancer is a little different than that of other cancers because your age at the time of your diagnosis plays a role. Patients under 45 years of age are all stage 1 unless there is evidence of spread outside of the head and neck.

Differentiated thyroid cancer:

PAPILLARY OR FOLLICULAR (DIFFERENTIATED)
Under 45 years old at diagnosis
Stage I Any T Any N M0
Stage II Any T Any N M1
PAPILLARY OR FOLLICULAR (DIFFERENTIATED)
45 years and older at diagnosis
Stage I T1 N0 M0
Stage II T2 N0 M0
Stage III T3 N0 M0
T1 N1a M0
T2 N1a M0
T3 N1a M0
Stage IVA T4a N0 M0
T4a N1a M0
T1 N1b M0
T2 N1b M0
T3 N1b M0
T4A N1b M0
Stage IVB T4b Any N M0
Stage IVC Any T Any N M1

Medullary thyroid cancer:

MEDULLARY THYROID CANCER
Stage I T1 N0 M0
Stage II T2 N0 M0
T3 N0 M0
Stage III T1 N1a M0
T2 N1a M0
T3 N1a M0
Stage IVA T4a N0 M0
T4a N1a M0
T1 N1b M0
T2 N1b M0
T3 N1b M0
T4a N1b M0
Stage IVB T4b Any N M0
Stage IVC Any T Any N M1

Anaplastic carcinoma:

ANAPLASTIC THYROID CANCER
Stage IVA T4a Any N M0
Stage IVB T4b Any N M0
Stage IVC Any T Any N M1

Your clinical stage

Once the diagnostic tests are completed, before deciding what type of treatment you are going to receive, you should be given a clinical stage that will look similar to the example below.

CLINICAL STAGE
Example
Site Thyroid
Age 34 years
Subsite Right lobe
Type Papillary
cT cT2
cN cN1a
cM cM0
cStage cI

* The lowercase c indicates that this is a clinical stage, the stage assigned based on all information available to your doctor before starting treatment.

After surgery, you should get a pathologic stage in regards to your tumor. It will look almost like the clinical stage you received before starting treatment, but notice the “p” that indicates the stage group is based on an analysis of the entire tumor, with or without lymph nodes, under a microscope by a pathologist. In many cases, the pathologic stage will be the same as the clinical stage, but sometimes it will change. You should consider the pathologic stage to be a more accurate assessment of your tumor at the time you start treatment.

After surgery, and after the pathologist has evaluated all of the tumor that was removed, you should be given a pathologic stage that looks something like this:

PATHOLOGIC STAGE
Example
Site Thyroid
Age 34 years
Subsite Right lobe
Type Papillary carcinoma, classical type
pT pT2
pN pN0
cM cM0
pStage pI

* The lowercase p indicates that this is a pathologic stage, the stage assigned after tumor removal and confirmation of cancer by a pathologist.

(See note from other section about why cM)

References

1 SEER Fast Facts. http://seer.cancer.gov/statfacts/html/thyro.html Accessed February 2013.

2 Hundahl SA, Fleming ID, Fremgen AM, et al.: A National Cancer Data Base report on 53,856 cases of thyroid carcinoma treated in the U.S., 1985-1995. Cancer. 1998;83:2638-2648.

3 Salerno P, De Falco V, Tamburrino A, Nappi TC, Vecchio G, Schweppe RE, Bollag G, Santoro M, Salvatore G. Cytostatic activity of adenosine triphosphate-competitive kinase inhibitors in BRAF mutant thyroid carcinoma cells. J Clin Endocrinol Metab. 2010;95(1):450-455.

4 Referenced with permission from The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Thyroid Carcinoma V.2.2013. © National Comprehensive Cancer Network, Inc 2013. All rights reserved. Accessed July 24, 2013. To view the most recent and complete version of the guideline, go online to www.nccn.org. NATIONAL COMPREHENSIVE CANCER NETWORK®, NCCN®, NCCN GUIDELINES®, and all other NCCN Content are trademarks owned by the National Comprehensive Cancer Network, Inc.

5 Cooper, D.S., G. M. Doherty, et al. (2009). “Revised American Thyroid Association Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer: the American Thyroid Association (ATA) Guidelines Taskforce on Thyroid Nodules and Differentiated Thyroid Cancer.” Thyroid 19(11): 1167-1214.

6 Ries LAG, Young JL, Keel GE, Eisner MP, Lin YD, Horner M-J (editors). SEER Survival Monograph: Cancer Survival Among Adults: U.S. SEER Program, 1988-2001, Patient and Tumor Characteristics. National Cancer Institute, SEER Program, NIH Pub. No. 07-6215, Bethesda, MD, 2007.