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Rectal Cancer (cont.)

What Is Rectal Cancer?

The rectum is the lower part of the colon that connects the large bowel to the anus. The rectum's primary function is to store formed stool in preparation for evacuation. Like the colon, the three layers of the rectal wall are as follows:

  • Mucosa: This layer of the rectal wall lines the inner surface. The mucosa is composed of glands that secrete mucus to help the passage of stool.
  • Muscularis propria: This middle layer of the rectal wall is composed of muscles that help the rectum keep its shape and contract in a coordinated fashion to expel stool.
  • Mesorectum: This fatty tissue surrounds the rectum.

In addition to these three layers, another important component of the rectum is the surrounding lymph nodes (also called regional lymph nodes). Lymph nodes are part of the immune system and assist in conducting surveillance for harmful materials (including viruses and bacteria) that may be threatening the body. Lymph nodes surround every organ in the body, including the rectum.

The American Cancer Society (ACS) estimates about 95,270 new cases of colon cancer and 39,220 new cases of rectal cancer will occur in 2016. Males are more likely than females to develop rectal cancer (about 23,110 males to 16,110 females in 2016). The most common type of rectal cancer is adenocarcinoma (98%), which is a cancer arising from the mucosa. Cancer cells can also spread from the rectum to the lymph nodes on their way to other parts of the body.

Like colon cancer, the prognosis and treatment of rectal cancer depends on how deeply the cancer has invaded the rectal wall and surrounding lymph nodes (its stage, or extent of spread). However, although the rectum is part of the colon, the location of the rectum in the pelvis poses additional challenges in treatment when compared with colon cancer.

This article only discusses issues related to rectal adenocarcinoma.

Medically Reviewed by a Doctor on 6/30/2016

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Read What Your Physician is Reading on Medscape

Rectal Cancer »

Approximately 135,000 new cases of colorectal cancer occur in the United States each year, resulting in approximately 55,000 deaths per year.

Read More on Medscape Reference »


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