NCCN Guidelines for Patients
Rectal Cancer, Version 1.2017
You’ve learned that you have rectal
cancer. It’s common to feel shocked and
confused. Part 1 reviews some basics that
may help you learn about rectal cancer.
Before learning about rectal cancer, it is helpful to
know about the rectum. The rectum is part of the
digestive system. This system breaks down food for
the body to use.
After being swallowed, food moves through four
organs known as the digestive tract.
See Figure 1
First, food passes through the esophagus and into
In the stomach, food is turned into a liquid. From
the stomach, food enters the small intestine. In the
small intestine, food is broken down into very small
parts. This allows nutrients to be absorbed into the
From the small intestine, food moves into the large
intestine. The large intestine changes unused food
from a liquid into a solid by absorbing water. This
solid, unused food is called feces or stool. The large
intestine also expels stool from the body through the
The rectum is part of the large intestine. It holds stool
until the stool is expelled from the body. The rectum
also triggers nerves that make you feel the urge to
have a bowel movement.
The rectum is almost 5 inches long. It is in the back
of your pelvis in front of your spine. It often contains
three folds that are shaped like a half moon.
Layers of tissue make up the rectal wall. The inner
layer that has contact with stool is called the mucosa.
The mucosa consists of three sublayers. They are
the epithelium, lamina propria, and muscularis
The epithelium makes mucus to help move stool
along. The lamina propria is a thin layer of support
(connective) tissue. The muscularis mucosae is a
thin strip of muscle.
The second layer of the rectal wall is called the
submucosa. It consists of connective tissue, blood
and lymph vessels, and nerve cells. Lymph is a clear
fluid that gives cells water and nutrients. It also has
white blood cells that fight germs. Blood and lymph
drain from rectal tissue into vessels that are in the
submucosa and then travel to other sites.
The third layer of the rectal wall is called the
muscularis propria. It is mostly made of muscle
fibers. These muscles help move stool through the
The last layer is a thin layer of connective tissue. It
has a single row of cells that make fluid. This fluid
allows the rectum to move smoothly against other
organs. This layer is called either subserosa or
The upper part and front of the mid rectal wall is
covered in serosa. The serosa, also called the
visceral peritoneum, is a membrane. It also covers
the front part of 1) the left and right sides of the colon
and 2) the kidneys.
Most of the rectum that isn’t covered in serosa is
covered in fat. The fat is thick in the middle of the
rectum. It thins out the closer it gets to the anus. This
fat is covered by connective tissue called the fascia
Rectal cancer basics