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Colon and Rectal Cancers - Introduction

From DrKoop's partner site on acid reflux, AcidRefluxConnection.com

Introduction


Cancers of the colon and rectum, often referred to collectively as colorectal cancer, are life-threatening tumors that develop in the large intestine.

More than 80% of colorectal tumors evolve from adenomatous polyp s. These gland-like growths develop on the mucous membrane that lines the large intestine. They are usually one of the following types:

  • Tubular polyps, which protrude mushroom-like
  • Villous adenomas, which are flat and spreading and are more apt to become malignant (cancerous)

It should be noted that these polyps are very common and almost always benign. Their numbers increase with age. Polyps are found in about 25% of people by age 50 and 50% of people by age 75. Fewer than 1% of polyps under 1 centimeter (slightly less than half an inch) become cancerous. About 10% of larger polyps become cancerous within 10 years, and about 25% of these larger polyps become cancerous after 20 years. Certain inherited polyps can become cancerous more rapidly.

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The Gastrointestinal Tract

Digestion takes place in the gastrointestinal (GI) tract, essentially a long tube that extends from the mouth to the anus. It is a complex organ system that first carries food from the mouth down the esophagus to the stomach. Food then travels through the small and large intestines before being excreted through the rectum and out the anus.
Digestive system
The esophagus, stomach, large and small intestine -- aided by the liver, gallbladder, and pancreas -- convert the nutritive components of food into energy and break down the non-nutritive components into waste to be excreted.

Esophagus

The esophagus is a narrow muscular tube, about nine and a half inches long that begins below the tongue and ends at the stomach.

Stomach

In the stomach, acids and stomach motion break food down into particles small enough so that the small intestine can absorb nutrients.
Stomach, lower esophageal sphincter, esophagus pictures Click the icon to see an image of stomach anatomy.

Small Intestine

The small intestine, despite its name, is the longest part of the gastrointestinal tract, extending for about 20 feet. Food passes from the stomach through its three parts: first the duodenum, then the jejunum, and finally the ileum. Most of the digestive process occurs in the small intestine.

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