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Norris Cotton Cancer Center
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Understanding Tumor Terminology

Terminology used to describe cancers, tumors, and tumor-like lesions can be confusing. We hope that these explanations may provide some clarity.

Lesion: Lesion is a term used by physicians to describe virtually any physical abnormality. It may refer to a tumor, a tumor-like condition, or a finding which is not yet diagnosed.

Tumor: A tumor is a term describing abnormal growth of a specific tissue or group of tissues. A tumor may be benign or malignant. The presence of a tumor does not mean you have cancer.

Tumor-like condition: Tumor-like conditions are normal findings which appear unusual on X-rays, MRI, or in a physical examination. These are among the most common lesions we see and generally require no treatment or just short-term observation. Tumor-like lesions may be the result of a previous trauma.

Neoplasm: A neoplasm is a tumor that originates from a single cell and undergoes multiple duplications. The rate of duplication determines the rate of growth of the tumor. Another term commonly used to describe a neoplasm is monoclonal tumor, meaning that the tumor arose from one (mono) cell (clone).

Benign: The term benign means that a tumor does not have the capacity to spread (metastasize) to other areas of the body. Benign tumors are far more common than malignant ones. The need and type of treatment required for a benign tumor is determined by the diagnosis, the tumor’s location, and whether the tumor is causing symptoms. Some benign tumors require treatment, others do not.

Malignant: A malignant tumor is one which has the capacity to spread (metastasize) to other areas in the body. A malignant tumor is commonly known as a cancer.

Cancer: Cancer is the general term used to describe a malignant tumor.

Metastasis: A metastasis occurs when a portion of a tumor which has left the original, or primary, tumor and traveled to another portion of the body. Sarcomas generally metastasize to the lungs, however, they may also travel to other locations.

Primary tumor: When metastasis has occurred, the term primary tumor is used to describe the original tumor which led to the metastasis.

Sarcoma: A sarcoma is a malignant tumor which arises from one or more connective tissues. These tissues include the bones, muscles, nerves, tendons, ligaments and adipose tissue (fat). Sarcomas are named by the tissue from which they arose, therefore sarcomas from the bone are generally osteosarcomas.