Cancer: A general term for more than 100 different diseases that involve the uncontrolled increase of abnormal new cells. These cells form tumors that can destroy surrounding tissue and spread throughout the body.

Cancer initiator: An agent that causes cells to mutate.

CBC: The complete blood count (CBC) quantitates the number of red blood cells (RBCs), white blood cells (WBCs), the total amount of hemoglobin in the blood, the fraction of the blood composed of cells (hematocrit), and the size of the red blood cells (MCV, mean corpuscular volume).

Carcinogen: A substance that initiates or promotes the development of cancer.

Chemotherapy: The treatment of cancer (or other disease) with chemicals that are toxic to the cancer cells.

Clark level of invasion: The method described by Dr. Wallace Clark for measuring the penetration of a primary melanoma into the skin by anatomic layer. Level I refers to melanomas confined to the outermost layer of the skin called the epidermis. (Another term for Level I melanoma is "melanoma in-situ".) Levels II-IV refer to different degrees of penetration into the second layer of the skin called the dermis. Level V refers to penetration into the third "fatty" layer of the skin called the subcutis.

Clinical trial: A study conducted with cancer (or other) patients, using the scientific method, to evaluate new therapies or procedures.

Collagen: A protein in the dermis made by fibroblasts that gives the skin its resilience and strength.

Control group: In a clinical trial, a group of subjects who receive standard treatment in order to compare the effects of the therapy under study with the effects of standard treatment.

Corticosteroids: Steroids produced by the adrenal cortex.

Cryotherapy: Super-freezing of tissue in order to destroy it. Used to treat malignant tumors, control pain, control bleeding, and reduce brain lesions.

CT scan: A CT scan X-rays the body from many angles. The X-ray beams are detected by the scanner and analyzed by a computer. The computer reconstructs the data into a picture of the body area being scanned. These images can be viewed on a monitor or reproduced as photographs.

Cure: To heal; to make well.

Cure rate: The percentage of patients who are cured.

Cutaneous: Related to the skin.

Cutaneous melanoma: Melanoma that starts in the skin.

Cytokines: Proteins released by the immune system that control several functions of the immune system.