Cancer is an overarching term that encompasses several disease states that can affect multiple areas in the body. Cancer can begin anywhere in the body and spread throughout.
In cancer, cells begin rapidly dividing without stopping, and this can lead to these cancer cells spreading to multiple sites within the body. Typically, the body monitors and regulates cell formation and growth, but these process are shut down in cancer which leads to the rapid growth of abnormal cells. Depending on the location of the cell growth, there is the potential for these cells to form solid masses known as tumors. If the origin of the cancer is the blood, you will not see tumor formation.
These tumors that form can either be benign or malignant. Benign tumors do not spread to other body parts or surrounding tissues. They typically are not life threatening and can be removed. Once they have been removed, they usually do not grow back. Malignant tumors have cells that spread to the surrounding tissues, and they may break off from the original mass and spread to other areas in the body via the blood or lymph systems. Malignant tumors are not the same as metastatic cancer. Metastatic cancer means that the cancer has spread from the site of origin to form an additional tumor in a new location.
Cancer is a genetic based disorder. This means cancer causing genes were either hereditary and something you were born with, or a genetic mutation was caused by an environmental exposure later in life. Environmental exposures can include tobacco smoke, ultraviolet rays, or radiation exposure. Cancer is not caused by a single genetic mutation, but typically a combination of multiple mutations that lead to abnormal cell growth. Having cancer can also result in even more genetic mutations as the disease progresses.
There are over 100 different types of cancer currently known. They are usually named based on the site where the cancer initially formed. Of these currently known cancers, carcinomas are the most common. A carcinoma is formed by epithelial cells, which line the inside and outside surface areas of the body. Another common type of cancer is sarcoma, which are formed from bones and soft tissues such as fats and muscles. Leukemias originate in the bone marrow where blood is formed. These cause large numbers of abnormal white blood cells to be found in the blood. Lymphomas also affect white blood cells, specifically T and B cells.