Anal Cancer

  • Medical Author: Jay B. Zatzkin, MD, FACP
  • Medical Editor: Charles Patrick Davis, MD, PhD
    Charles Patrick Davis, MD, PhD

    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

Quick GuideSTD Diagnosis, Images, Symptoms, Treatment

STD Diagnosis, Images, Symptoms, Treatment

Anal anatomy

The anus is the lowest end of the gastrointestinal (GI) tract. It is the opening through which stool, or fecal matter, normally passes. The anal canal extends from the lower end of the rectum to the skin; this is where anal cancer occurs while colorectal cancer occurs in the rectum and colon. This canal is surrounded by muscles forming the internal and external anal sphincters that allow us to control when we defecate, or have a bowel movement. The perianal skin surrounds the anus in the perineal region behind either the vaginal orifice or the scrotum.

What is anal cancer?

Cancers arise in areas of the body when some of the cells of a tissue become abnormal in both their gross and microscopic appearance and in their behavior. These malignant cells can damage adjacent healthy tissue cells by directly invading them. Cancer cells also have the ability to invade blood vessels and lymphatic channels and spread, or metastasize, to other parts of the body.

While anal cancer begins in the anus, people sometime confuse it with colorectal cancer, which occurs in the colon and/or rectum.

What are the different types of anal cancer?

The majority of primary cancers of the anus are squamous cell carcinomas. Other types of anal cancers include

  • cloacogenic (also called basaloid or transitional anal cancer),
  • adenocarcinoma of the anal glands, and
  • melanoma (rare).

What are other types of anal masses or growths?

Not all growths in the anal region are cancers. A benign growth of tissue on a short stalk is called a pedunculated polyp. A flat-bottomed growth is called a sessile polyp. The sessile polyps are more likely to show precancerous or cancerous change microscopically.

Medically Reviewed by a Doctor on 4/28/2017

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