One way that cancer spreads through the body is through the lymphatic system which the lymph nodes are a part of. The cancer cell detaches from the primary tumor and it travels in the lymphatic fluid until it gets stuck in the small channels inside a lymph node where a secondary cancer begins. When this process occurs it is called metastasis.
What are Lymph Nodes?
- part of the lymphatic system
- bean shaped structures as small as a pin head to the size of a lima bean
- serve as channels for the extra cellular fluid around the cells to return into the blood stream
- act as filters for bacteria, fungi and viruses
- the white blood cells and antibodies in the lymph nodes fight diseases
Doctors will test the nodes for traces of cancer cells to help determine the stage of the cancer. The sentinel lymph node is the first node that a tumor drains into making it the first place that cancer cells will likely spread too.
When diagnosed with cancer of the thyroid gland, the nodes belonging to the lymphatic system in the area will be checked. Papillary thyroid cancer is the most common thyroid cancer. The spread to nodes, cervical metastasis, occurs in 50% of small tumors and over 75% of the larger thyroid tumors.
When the lymph nodes are enlarged because of the papillary thyroid cancer, a surgical procedure called a modified neck dissection will have to be performed. If both sides of the neck have nodes that have traces of papillary thyroid cancer cells the two surgeries will be done in two different procedures about 6-8 weeks apart. This is done to allow the one side to heal and so new pathways for blood and lymph flow to form for proper drainage from the head and neck area.
The lymph nodes may also be affected in the other types of thyroid cancer.
- Follicular cancer of the thyroid, the second most common, does not usually spread to the nodes, but may spread to the veins and arteries of the thyroid gland and very uncommonly to other organs.
- Medullary cancer of the thyroid, the third most common, will usually spread to the nodes of the lymphatic system earlier than follicular and papillary thyroid cancers.
- Anaplastic thyroid cancer, the most serious, will spread very early to the lymph nodes. The enlargement of the nodes is usually the reason the patient will go to the doctor. This type of thyroid cancer is the most likely to spread to other organs beyond the thyroid and lymph nodes.
Age is the major factor when determining the prognosis of the different types of cancers that affect the thyroid gland. Whether the nodes surrounding the cancerous thyroid gland are affected, or the cancer extends into the veins or is outside of the tissue that encloses it, people of a young age will rarely die from their disease. As an older person all this factors come into play when diagnosed and in long term survival disease free.