What Is Anal Cancer
Cancer describes a set of diseases in which normal cells in the body, through a series of genetic changes, lose the ability to control their growth and to respect their neighbors. As cancers grow, they invade the tissues around them (local invasion). They may also spread to other locations in the body via the blood vessels or lymphatic channels where they may implant and grow (metastases). Tumors, or growths in the body, may be benign or malignant (cancerous). When they are benign they may grow but they do not spread to other locations. Malignant tumors have the ability to invade deeply and to spread (metastasize).
Anal cancer arises from the cells around the anal opening (verge) or within the anal canal (1-2 inches long) up to its junction with the rectum. Most anal cancers arise from skin cells and are called squamous cell carcinomas. Some arise from the special mucosal cells lining the upper anal canal and are called cloacogenic carcinomas. Although several other types of cancer may occur in this area, these two are the most common. They behave similarly and are treated in the same fashion. Cells that are becoming malignant but have not invaded below the surface are "pre-cancerous" (carcinoma-in-situ). This condition is called Bowen's disease.
What Is Anal Cancer
