THYROID LUMPS AND CANCER

What is Thyroid Cancer?

Thyroid gland is an endocrine gland located in the lower neck. It secretes a very important hormone called thyroxine in to the blood stream. Thyroxine travels to most of the organs and plays a crucial role in the normal functioning of the organs. So it is very important for over all well being . Even thyroid gland can develop cancer. But thyroid gland cancers are considered to be indolent compared to other cancers, though there are few exceptions.

Types of Thyroid Cancers

Papillary thyroid cancer

It is the most common type of thyroid cancer developing from follicular cells .It is a differentiated thyroid cancer, meaning that the tumor resembles normal thyroid tissue under a microscope. Papillary thyroid cancer is slow growing but can often spread to lymph nodes. It is usually found in one lobe but 30% of them can occur in other lobe also. It has very good prognosis.

Follicular thyroid cancer

Follicular thyroid cancer also develops from follicular cells and is also a differentiated thyroid cancer, but it is less common than papillary thyroid cancer. Follicular thyroid cancer spreads through blood stream and rarely spreads to lymph nodes. Just like papillary cancer follicular cancer also has good prognosis especially in patients who are aged less than 50 years.

Follicular and papillary thyroid cancers make up about 95% of all thyroid cancer.

Medullary thyroid cancer

Medullary thyroid cancer develops from C cells. This tumor has very little, if any, similarity to normal thyroid tissue. It accounts for about 3% of all thyroid cancers. About 25% of medullary thyroid cancer is hereditary. Patients with multiple endocrine neoplasia syndrome II have medullary thyroid cancer. 75% of them is sporadic. It can be cured if diagnosed early before it spreads to other parts of the body. It doesn’t resemble normal thyroid tissue under microscope.

Anaplastic thyroid cancer

Though rare, accounting for only 1% of thyroid cancer, it is the most aggressive form of thyroid cancer. It is a rapidly growing, poorly differentiated thyroid cancer. It is difficult to treat as it usually presents in advanced stage.

Stages of Thyroid Cancer

  • TNM staging where T stands for tumor size, N stands for nodal status, M stands for distant spread.
  • TX: The primary tumor cannot be evaluated.
  • T0: There is no evidence of a tumor.
  • T1:The tumor is less than 2 centimeters.
    • T1a: The tumor is 1 cm or smaller.
    • T1b: The tumor is larger than 1 cm but less than 2 cm.
  • T2: The tumor is larger than 2 cm but smaller than 4 cm.
  • T3:The tumor is larger than 4 cm, but the tumor does not extend beyond the thyroid gland.
  • T4: The tumor of any size with extension beyond the thyroid.
    • T4a: The tumor has spread beyond the thyroid to nearby soft tissues, the larynx, trachea, esophagus, or recurrent laryngeal nerve.
    • T4b: The tumor has spread beyond the regions in T4a like carotid artery.
Node(N)

There are many regional lymph nodes located in the head and neck area to which thyroid cancer can spread.

  • NX: The regional lymph nodes cannot be evaluated.
  • N0:There is no evidence of cancer in the regional lymph nodes.
  • N1: Cancer has spread to the lymph nodes.
    • N1a: Cancer has spread to the lymph nodes around the thyroid, central compartment; the pretracheal, paratracheal, and prelaryngeal lymph nodes and to mediastinal lymphnodes.
    • N1b: Cancer has spread beyond the central compartment, including unilateral cervical (lymph nodes on 1 side of the neck), bilateral cervical (lymph nodes on both sides of the neck), contralateral cervical (the opposite side of the tumor).
Metastasis(M)
  • MX: Distant metastasis cannot be evaluated.
  • M0: Cancer has not spread to other parts of the body.
  • M1: Cancer has spread to other parts of the body.
Papillary or follicular thyroid cancer in a person younger than 55

Stage I: This stage describes a tumor (any T) with or without spread to lymph nodes (any N) and no distant metastasis (M0).

Stage II: This stage describes a tumor (any T) with any metastasis (M1) regardless of whether it has spread to the lymph nodes (any N).

Papillary or follicular thyroid cancer in a person 55 and older

Stage I: This stage describes any small tumor (T1) with no spread to lymph nodes (N0) and no metastasis (M0).

Stage III: This stage describes a tumor larger than 4 cm but still contained in the thyroid (T3) with no spread to lymph nodes (N0) and no metastasis (M0). Or, any localized tumor (T1, T2, or T3) with spread to the central compartment of lymph nodes (N1a) but no distant spread (M0).

Stage IVA: This stage describes a tumor that has spread to nearby structures (T4a), regardless of whether it has spread to the lymph nodes (any N), but it has not spread to distant places (M0). Or, this describes a localized tumor (T1, T2, or T3) with lymph node spread beyond the central compartment (N1b) but no distant spread (M0).

Stage IVB: This stage describes a tumor that has spread beyond nearby structures (T4b), regardless of spread to lymph nodes (any N), but no distant spread (M0).

Stage IVC: This stage describes all tumors (any T, any N) when there is evidence of metastasis (M1)

Medullary thyroid cancer

Stage I:This stage describes a small tumor (T1) with no spread to lymph nodes (N0) and no distant metastasis (M0).

Stage II: This stage describes a larger localized tumor (T2 or T3) with no spread to lymph nodes (N0) and no metastasis (M0).

Stage III: This stage describes any localized tumor (T1, T2, or T3) that has spread to the central compartment of lymph nodes (N1a) but has not metastasized (M0).

Stage IVA: This stage describes a tumor that has spread to nearby structures (T4a), regardless of whether it has spread to the lymph nodes (any N), but it has not spread to distant places (M0). Or, this describes a localized tumor (T1, T2, or T3) with lymph node spread beyond the central compartment (N1b) but no distant spread (M0).

Stage IVB: This stage describes a tumor that has spread beyond nearby structures (T4b), regardless of spread to lymph nodes (any N), but no distant spread (M0).

Stage IVC: This stage is used when there is evidence of metastasis (any T, any N, M1).

Anaplastic thyroid cancer

Stage IV: All anaplastic thyroid tumors are classified as stage IV, regardless of tumor size, location, or metastasis.

Stage IVA: This stage describes an anaplastic tumor that has spread to nearby structures (T4a), regardless of whether it has spread to the lymph nodes (any N), but it has not spread to distant places (M0).

Stage IVB: This stage describes an anaplastic tumor that has spread beyond nearby structures (T4b), regardless of spread to lymph nodes (any N), but no distant spread (M0).

Stage IVC: This stage is used when there is evidence of metastasis (any T, any N, M1).