Cancer is a term used to describe over a hundred different diseases with certain features in common. A cancer begins with a change in the structure and function of a cell that causes the cell to divide and multiply out of control. The cells can subsequently invade and damage surrounding tissues, and cells can break away and spread to other areas in the body. A cancer is generally named for the organ or type of cell in which it first begins to grow.

Cancers are generally classified as solid tumors and liquid tumors. Solid tumors begin in an organ of the body, such as the breast or lung. Liquid tumors begin in the bone marrow or lymphatic system, which carries fluids throughout the body. Examples are leukemia (cancer of the blood or bone marrow), lymphoma (cancer in the lymphatic system), and multiple myeloma (cancer of the plasma cells in the blood).

When you speak with your doctor or read information about your cancer, you’ll find it easier if you understand the terms often used in speaking about cancer. A tumor is any abnormal mass or swelling in the body.

Looking at a sample of the tumor cells under a microscope, a pathologist can determine whether it is a benign (noncancerous) tumor or a malignant (cancerous) tumor. The pathologist can also determine the tumor’s grade, which is a measure of how abnormal the cells appear when examined under a microscope; in some cases, grade predicts how aggressive the cancer is. The stage is a measure of whether or not or how much the cancer has spread. To determine the stage, the doctor might order a variety of tests, such as blood tests, computed tomography (CT), magnetic resonance imaging (MRI), radionuclide scanning (e.g., bone scan), positron emission tomography (PET), and, in some types of cancer, samples of bone marrow.

Most types of cancer progress through four stages:

• In Stage I, the tumor is localized to a small area within the organ in which it started.

• In Stage II, the cancer has spread to the lymph nodes in the area. (Lymph nodes are bean-shaped structures in the lymphatic system that filter lymph fluid before it is returned to the bloodstream.)

• In Stage III, the tumor is locally advanced (i.e., a cancerous tumor has spread to surrounding structures).

• In Stage IV, the tumor has metastasized (i.e., a cancerous tumor has spread to a distant site, such as the bones, the liver, or the brain).

For most cancer types, the stages are defined by the American Joint Committee on Cancer (AJCC).

To learn more about staging, go to www.cancerstaging.org

Terms:

Tumor - An abnormal swelling or mass in the body.

Benign - Noncancerous.

Malignant - Cancerous.

Grade - A measure of how abnormal a cell appears when examined under a microscope; in some cases, grade predicts how aggressive the cancer is.

Stage - A measure of how extensive the cancer is, that is, how much it has spread

Lymph nodes - Bean-shaped structures in the lymphatic system that filter lymph fluid before it is returned to the bloodstream.

Locally advanced - A cancerous tumor has spread to surrounding structures.

Metastasized - A cancerous tumor has spread to a distant site, such as the bones, the liver, or the brain