A Quick Guide to Cancer Basics
After cancer is diagnosed, you will hear several terms, including:
- The medical name of the tumor
- The stage of the cancer
- The grade of the cancer.
The type of the cancer is determined by the organ it starts in, the type of cell from which it is derived, and the appearance of the cancer cells. There are numerous ways to name the various types of cancers. In general, these names come from Latin prefixes that are associated with the location where the cancer originates. For example, cancer that starts in the bone is called osteosarcoma ("osteo" is Latin for "bone").
If a cancer has spread (metastasized), it will still have the same name as the original cancer. This means that if a cancer originates in the brain but has spread to the lung, it would be called metastatic brain cancer, not lung cancer.
The stage describes how far the cancer has spread. Knowing this helps doctors determine which treatment to use. Although staging may not apply to all forms of cancer, such as some forms of leukemia, there are basically two staging systems: the overall stage grouping and the Tumor, Node, Metastases (TNM) system.
For overall grouping, there are four stages: stage I, stage II, stage III, and stage IV. While this can become quite complicated, basically, stage I cancers are small, localized cancers that are usually curable, while stage IV cancers are usually inoperable or metastatic. How the stages are determined will vary, depending on the type of cancer you have and various other factors.
If you have a solid tumor, a more detailed staging system is used called the TNM system. With this process, each of these categories is staged separately using a number system, as follows:
- T classifies the extent of the primary tumor, from T0 to T4. A T0 tumor has not started to invade the local tissue, but a T4 tumor has probably invaded other organs and is usually inoperable.
- N classifies how much the lymph nodes are affected. N0 means no lymph node involvement, and N4 means extensive involvement.
- M classifies whether there are any metastases. M0 means there are none, while M1 means there are metastases.
For leukemia and other cancers that don't form a solid tumor, the staging is different. These types of cancers are often defined as stages I through IV, but it will depend on factors such as blood count and bone marrow involvement. Also, some types of cancer may be staged by A through D, rather than by I through IV.
The tumor grade is how abnormal cells from the tumor look under the microscope. This can include the appearance of the cells or the percentage that appear to be dividing. In short, the higher the grade, the more aggressive and fast growing the cancer. Grades are usually classified from least to most aggressive as grade I through IV.
Although knowing what stage and grade your cancer is can be helpful, it is not the whole story. Try not to get too wrapped up in what the stage and grade of your cancer are, as there is considerable variation in outcome for every type and stage. These classifications are mainly used to help your medical team determine the best course of treatment for your particular situation.