Stages of cancer are used to describe the severity of the cancer. Determining what stage the cancer is at diagnosis is critical in determining what path to take for treatment. In most cases, there will be an initial biopsy to test for cancer, and then subsequent tests will be needed to identify the stage of cancer.
The stages of cancer are not entirely set in stone, as cancer advances differently depending on what system of the body is being affected. New advancements are made in cancer research continually, so the definition of the different stages are often altered to include new findings. Physicians and scientists use the stages of cancer as a basic guideline, each case is different, and all cancer patients will not necessarily go through each stage.
Elements Considered in Stages of Cancer Systems
The most common elements that are considered when determining cancer staging include:
- Size of tumor
- Site of the tumor and cell type
- How closely the infected cells resemble uninfected cells-called tumor grade
- Whether the cancer has spread to the lymph nodes
- Number of tumors
Numerical Classification for Stages of Cancer
Cancer is typically classified as being stage zero through stage four. Stage zero cancer is also referred to as “in situ”. This means that the cancer has been caught before it has spread at all, and only a single or a few cells are corrupted by a tumor. At this stage, the cancer is not harmful and poses no risk. However, cancer can quickly move from this stage if the conditions are right and treatment is not pursued.
Stage One Cancer
Stage one cancer begins when the cancer spreads to a localized area. At this stage, cancer is still not spreading rapidly in most cases, and is only present in the initial cell or cells and cells immediately surrounding the area. When cancer moves into this stage, it has shown the ability to pass through the basement membrane, which is the membrane surrounding the originally infected cell. This is dangerous, because the cancer has shown the ability to invade healthy tissue, which is a threat to health and life.
Stage Two Cancer
In stage two cancer, the area that is affected by cancer is still small, but the cancer may have begun to spread into the lymph tissues. When speaking of breast cancer, the physician may classify the cancer as stage IIA or stage IIB. In stage IIA, there may be no tumor present, but the lymph nodes may test positive for cancer. There may also be a tumor that is two centimeters or less with lymph invasion, or a tumor between two and five centimeters with no cancer presence in the lymph nodes. In stage IIB, the tumor may be larger than five centimeters, with no cancer present in the lymph nodes; or the tumor may be between two and five centimeters with the presence of cancer in the lymph nodes.
Stage Three Cancer
Stages two and three are often referred to as regionalized cancer, and are sometimes classified together depending on the system of the body that is affected. In stage three cancer, the cancer has often spread into the lymph nodes. Sometimes there is also a spread into the muscle tissue, but the cancer has not yet invaded organs. In breast cancer, there may be a more specific classification-stage IIIA, B, or C. These classifications are used to quickly identify the presence or lack of tumors, size of tumors, and severity of invasion into the lymph systems. Stage IIIC may be inoperable. This means that surgery is not an option to get rid of all of the cancer; however other forms of treatment may still be effective.
Stage Four Cancer
Cancer that has reached stage four can vary greatly in characteristics. Generally, cancer that has reached this stage is considered to be a distant spreading cancer. This means that the cancer has spread far from the original site. At this point, cancer can spread from the lymph nodes or original body cells into the blood stream. Once the cancer has entered the blood stream, it is very difficult to contain and treat, as it can quickly spread to other areas.
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