Staging of medullary thyroid cancer

The most common staging system is the TNM system.

T describes the size of the tumour and whether it has spread into nearby tissues around the thyroid gland.

N describes whether the cancer has spread to the lymph nodes close to the thyroid gland.

M describes whether the cancer has spread to other parts of the body, such as the lungs or the bones (metastatic).

Doctors put a number next to the T to describe the size and spread of the cancer.

T1 means the tumour is 2cm or less and has not grown outside the thyroid gland.

• T1a means the tumour is 1cm or smaller.
• T1b means the tumour is between 1cm and 2cm.

T2 means the tumour is between 2cm and 4cm. It has not grown outside the thyroid gland.

T3 means the tumour is bigger than 4cm or it has grown slightly outside the thyroid gland.

• T3a means the tumour is bigger than 4cm and has not grown outside the thyroid gland.
• T3b means the tumour is of any size and has grown slightly outside the thyroid gland to nearby muscles.

T4 means the tumour has grown outside the thyroid gland and is attached to nearby structures.

• T4a means the tumour has started to grow into nearby structures, such as the voicebox (larynx), windpipe (trachea), gullet (oesophagus) or the voicebox nerve (recurrent laryngeal nerve).
• T4b means the tumour has grown into the area close to the spine or into a major blood vessel in the neck or upper chest.

The N may have a number written next to it. This gives information about the nodes that were examined.

N0 means the lymph nodes are not affected.

N1 means the cancer has spread to lymph nodes close to the thyroid gland or in the neck or chest area.

• N1a means the cancer has spread to lymph nodes in the middle of the neck, close to the thyroid gland.
• N1b means the cancer has spread to lymph nodes in one or both sides of the neck or the upper part of the chest.

The M may have a number written next to it. This gives information about whether the cancer has spread.

M0 means the cancer has not spread to other parts of the body.

M1 means the cancer has spread to another part of the body.

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