NCCN Guidelines for Patients
Colon Cancer, Version 1.2014
6 What is the colon?
8 How colon cancer starts and spreads
Learning that you have cancer can
be overwhelming. This chapter briefly
describes what colon cancer is. These
basics may help you cope and better
understand Parts 2 through 8.
What is the colon?
The digestive system breaks down food for the
body to use. After being swallowed, food moves
through four organs known as the digestive tract as
First, food passes through the
esophagus and into the stomach. The stomach turns
solid food into a liquid. From the stomach, food enters
the small intestine where food is broken down into
very small parts and nutrients are absorbed into the
After the small intestine, food moves into the large
intestine. The large intestine changes unused food
from a liquid into a solid form by absorbing water. This
solid, unused food is called feces or stool. The large
intestine also expels stool from the body. The colon is
part of the large intestine. It is almost 5 feet long. Its
four parts are the ascending, transverse, descending,
and sigmoid colon.
The wall of the colon has four main layers as shown
The inner layer that has contact with
stool is called the mucosa. The mucosa is made of
three sublayers—the epithelium, lamina propria, and