Cancer is not one disease, but many diseases that occur in different areas of the body. Each type of cancer is characterized by the uncontrolled growth of cells. Under normal conditions, cell reproduction is carefully controlled by the body. However, these controls can malfunction, resulting in abnormal cell growth and the development of a lump, mass, or tumor. Some cancers involving the blood and blood-forming organs do not form tumors but circulate through other tissues where they grow. There is no longer a “one-size-fits-all” approach to cancer treatment. Even among patients with the same type of cancer, the behavior of the cancer and its response to treatment can vary widely. By exploring the reasons for this variation, researchers have begun to pave the way for more personalized cancer treatment. Precision cancer medicine utilizes molecular diagnostic testing, including DNA sequencing, to identify cancer-driving abnormalities in a cancer’s genome. By defining the consequences of these genetic abnormalities doctors can identify specific treatments directed against each genetic abnormality for each individual patient’s unique DNA profile. Once a genetic abnormality is identified, a specific targeted therapy can be designed to attack a specific mutation or other cancer-related change in the DNA programming of cells. Standard chemotherapy typically destroys both normal and cancerous rapidly dividing cells in a wide range of tissues, often causing side effects by damaging normal cells. Precision cancer medicine uses targeted therapies engineered to directly attack the cancer cells with specific abnormalities, leaving normal cells largely unharmed.
A tumor may be benign (non-cancerous) or malignant (cancerous). Cells from cancerous tumors can spread throughout the body. This process, called metastasis, occurs when cancer cells break away from the original tumor and travel in the circulatory or lymphatic systems until they are lodged in a small capillary network in another area of the body. Common locations of metastasis are the bones, lungs, liver, and central nervous system.
The type of cancer refers to the organ or area of the body where the cancer first occurred. Cancer that has metastasized to other areas of the body is named for the part of the body where it originated. For example, if breast cancer has spread to the bones, it is called “metastatic breast cancer” not bone cancer.