Cancer is not just one disease. Rather, it’s a group of diseases, all of which cause cells in the body to change and grow out of control. Cancers are classified by the kind of fluid or tissue from which they come from. Or they can be classified due to the location in the body where they first started. Some cancers are of mixed types. These categories are the tissue and blood classifications of cancer:
- Carcinoma. A carcinoma is a cancer found in body tissue called epithelial tissue. It covers or lines surfaces of organs, glands, or body structures. For instance, a cancer of the lining of the stomach is called a carcinoma. The two most common types of carcinomas are include squamous and adenocarcinomas. Many carcinomas affect organs or glands that are involved with secretion. These include breasts that make milk. Carcinomas account for 80 percent to 90 percent of all cancers.
- Sarcoma. A sarcoma is a malignant tumor growing from connective tissues. These can include cartilage, fat, muscle, tendons, and bones. The most common sarcoma, a tumor on the bone, usually occurs in young adults. Examples include osteosarcoma (bone) and chondrosarcoma (cartilage).
- Lymphoma. Lymphoma is a cancer that starts in the nodes or glands of the lymphatic system. The lymphatic system makes white blood cells and cleans body fluids. Some lymphomas start in lymph tissue in organs. These include the brain or stomach. Lymphomas are classified into two categories: Hodgkin lymphoma and non-Hodgkin lymphoma.
- Leukemia. Leukemia is also known as blood cancer. It’s a cancer of the bone marrow that keeps the marrow from making normal red and white blood cells and platelets. White blood cells are needed to fight infections. Red blood cells are needed to prevent anemia. Platelets keep the body from bruising and bleeding easily. Examples include acute myelogenous leukemia, chronic myelogenous leukemia, acute lymphocytic leukemia, and chronic lymphocytic leukemia. The terms myelogenous and lymphocytic indicate the type of cells that are involved.
- Myeloma. Myeloma grows in the plasma cells of bone marrow. In some cases, the myeloma cells collect in one bone and form a single tumor. This is called a plasmacytoma. However, in other cases, the myeloma cells collect in many bones, forming many tumors. This is called multiple myeloma.
What causes cancer?
Cancer has no single cause. Experts think that it’s the interaction of many factors that leads to cancer. The factors may be genetic, environmental, or lifestyle characteristics.