Before studying the concept of thyroid cancer it is useful to remember the peculiarities of thyroid gland and clarify the notion of cancer as an illness.
The thyroid gland is located in the neck and resembles a butterfly in shape. It consists of two lobes that are separated by isthmus. A normal healthy thyroid does not exceed a quarter and is not seen or felt. In its swollen form it is called goiter. The latter may result from the scarcity of iodine in a person’s daily allowance. Thyroid gland contains two types of cells that produce hormones. The first are follicular cells that are responsible for the production of thyroid hormone. Its task is to influence heart rate, body temperature, and energy level. The second type of cells created by the gland is C cells. These cells create calcitonin, a hormone which purpose is to control the blood calcium level.
Cancer can affect any part of the body. The disease starts to develop in cells. In a healthy organism cells grow and then divide from new ones; when they get old and die and are replaced by new cells. But there happens something that makes the whole process go the wrong way. New cells develop when the body has no necessity in them and old cells do not die in time therefore forming excess of tissue also called growths or tumors. The ones found on the thyroid bear the name of nodules.
These nodules can be benign or malignant. The former are not considered cancer because these cells have no tendency to spread to other parts of the body. 90% of the thyroid nodules are considered benign. The latter tumors (malignant) are cancerous and can be very severe and in some cases even dangerous. These cells are able to spread and affect adjoining tissues and organs; it also enters the bloodstream and the lymphatic system and therefore forms new tumors. This process is called metastasis.
Thyroid cancer has several types. Papillary and follicular thyroid cancers are the most widespread types and are treated successfully in case they were detected in time. They start to form in the follicular cells and are characterized by slow speed of growth and development. Another form of thyroid cancer is medullary thyroid cancer and it is not as widespread as the previous two. It originates from C cells and is treated easier if detected before it metastasizes. Anaplastic thyroid cancer is the rarest and has the most abnormal cell forms that are hard to recognize. This type of cancer originates from follicular cells and is extremely hard to control because of the great speed the cells grow and spread at.
In cases when metastases appear cancer cells are detected in lymph nodes, nerves, or blood vessels. Provided cancer reached lymph nodes the lungs or bones can be affected as well. Metastases create new tumors that consist of the same cells that the primary tumor has. This means that cancer cells found in lungs will be thyroid cancer cells and the illness will be metastatic thyroid cancer, not lung cancer and therefore should be treated as such. New tumors are often called “distant” or metastatic disease.