Source: Cancer Resource Room
What is Colon Cancer?
Any cancer that starts in the colon (large intestine) is
called colon cancer. Cancers are formed by abnormal
cells that grow and divide without control. These cancer
cells replace normal cells and form a tumor or lump.
As a tumor gets bigger, it can grow into nearby tissues
and organs. Cancer cells can spread to other parts of
the body through the blood or lymph vessels. Most colon
cancers start in the cells that line the inside of the
large intestine. Tumor cells grow there, invade through
the layers of the colon, and spread to lymph nodes and
other tissues. Colon cancer is one of the most common
cancers in the US, with about 130,000 new cases a year.
What is the colon and what does it do?
The large intestine (colon) is the last part of the digestive
system before wastes leave the body.
The colon is divided into five parts:
- cecum - part closest to the small intestine
- right colon
- transverse colon – part that connects the right
- left colon
- sigmoid colon - part just above the rectum
The large intestine is separated from the small intestine
by a circle of muscle called the ileocecal valve. It controls
the flow of fluid from the small to the large bowel. The large
intestine absorbs water and some nutrients, and eliminates
wastes from our diets.
There are five layers of tissue that make up the colon:
- lining layer (lamina propria)
- muscular layer for the lining (muscularis mucosa)
- support tissue for lining layers (submucosa)
- muscle (muscularis)
- outside covering layer (serosa)
Colon cancer usually starts in the lining layer. It grows
larger and deeper through the other layers, spreading to nearby
tissues and lymph nodes. The tumor can make a hole in the
colon into the abdomen or into another organ. The intestines
can keep working even though a cancer has started in one part
of it. This means a colon cancer can get quite large or deep
before it is diagnosed.
What are the symptoms of
Symptoms caused by colon cancer are from the tumor
taking up space inside the intestine, from the loss of small
amounts of blood from the tumor into the bowel, and from the
tumor growing through the intestine into the abdomen or other
organs. A tumor can cause a blockage or obstruction so the
stool cannot pass by easily. The cancer tissue can bleed into
the intestine, making the person anemic. Some symptoms are
caused by cancer cells invading other tissues or putting pressure
on nerves. Colon cancer usually grows for some time before
it causes any symptoms. When symptoms occur they include:
- abdominal pain
- change in bowel habits
- weight loss (without dieting)
- weakness or tiredness (due to anemia—a low blood
- nausea and vomiting
- swelling of the abdomen
- rectal bleeding
- bloody or black, sticky bowel movements
- rectal pain
These symptoms can have other causes and should be checked
by a doctor.
How is colon cancer diagnosed?
A patient’s medical history and physical exam
are the first steps in making a diagnosis of any disease.
The medical history includes many details of a person’s
health. In particular, the history will focus on the digestive
tract—changes in eating habits, changes in bowel movements,
abdominal pain or bloating, and how food affects any of the
symptoms. In the case of colon cancer, the patient’s
history may include information about other diseases such
- inflammatory bowel disease
- granulomatous colitis
- previous colorectal cancer or polyps
- radiation of the pelvis
- GI surgery in the past, including gallbladder removal
- family history of polyps or colon cancer
The physical exam will focus on areas of discomfort in the
abdomen, the presence of a mass (a lump) in the abdomen, an
enlarged liver, fluid or swelling in the abdomen, any skin
color change (yellow jaundice), or enlarged lymph nodes. The
stool must be checked for blood. The rectum and anus need
to be checked for lumps by digital (finger) exam.
After the history and physical exam, some diagnostic tests
may be ordered. Blood tests and a chest x-ray check a patient’s
general health. Some blood tests that may be done include:
- Blood count- to check for anemia and iron deficiency
- Liver enzymes- for possible spread to the liver
- CEA-marker protein that may increase
Special tests that are useful in diagnosing colon cancer
- CT scan—x-rays made in thin cross-sections of the
abdomen. This set of x-rays can show a tumor in the colon,
as well as its spread to nearby tissues and lymph nodes.
This test is especially useful for finding disease spread
to the liver.
- Colonoscopy—this test uses a thin, flexible tube
with a camera in it to look at the inside of the colon (large
intestine) and rectum. The camera images are displayed on
a TV monitor allowing the doctor to see the inside of the
entire large intestine. The colonoscope is passed through
the anus and rectum into the colon and up through the large
intestine. A biopsy can be taken of any tissue that looks
abnormal. Lumps of tissue inside the colon called polyps
can be removed. In preparation for the test, the patient
drinks only liquids the day before, including a fluid that
helps clean out the bowel. The procedure is done using sedation
for relaxation. It is not a painful procedure and does not
What is a biopsy? What does it mean to a patient?
A biopsy is a small piece of tissue or group of cells used
to diagnose a disease. The tissue is taken from a spot suspected
of being abnormal. Then the biopsy tissue is looked at under
a microscope by a pathologist. The diagnosis is based on the
appearance of the tissue and cells. The biopsy result is used
to decide the patient’s treatment.
What if the biopsy shows colon cancer?
If the biopsy shows cancer, the next step is to find out
how much disease there is. You need to know:
- how widespread is the disease in the colon
- how many layers has it spread through
- has it spread beyond the colon into the lymph nodes, into
nearby tissues, or to distant lymph nodes and other organs
What tests are used to find the spread of colon cancer?
- CT scans—these are X-rays that show cross-section
pictures of the body. CT images let the radiologist see
the abdominal organs in many ways, going across, as well
as up and down, the body. An abdominal CT scan shows the
stomach, lymph nodes, liver, gallbladder and bile ducts,
pancreas, small and large intestines, kidneys, major blood
vessels, and part of the spine. The patient may need to
drink a contrast solution to help outline the digestive
organs. An IV is used to give the patient contrast “dye”
that travels through the blood. Contrast dye in the blood
makes a person feel very warm for a brief time, and causes
a sensation of needing to pee urgently. Both feelings pass
quickly. CT scans are not painful but do require lying on
a table for about 30 minutes.
- Laparoscopy—this procedure lets the surgeon look
inside the abdomen with a laparoscope, a thin tube with
a small camera in the end. The laparoscope is inserted through
a small abdominal incision. It transmits pictures from inside
the abdomen to a TV monitor so the surgeon can see what
tissues look normal and which do not. This helps plan the
patient’s surgery and other treatments. This procedure
is used for small intestine disease much more often than
for colon cancer. Laparoscopy is done in the operating room
with the patient under general anesthesia.
The information about the patient including the medical history,
physical exam, blood tests, x-rays, special scans, and procedures
are used to describe the patient’s stage of disease
and plan the best treatment for that disease.
What is the stage of a cancer? How is it determined?
The stage of a cancer describes how much cancer there is,
what tissue it has invaded, and whether or not it spread to
lymph nodes and other parts of the body. The higher the stage,
the more complicated the disease. The stage is a combination
of the size of tumor growth, the number of lymph nodes involved,
and the spread to other sites (metastases). For colon cancer,
there are at least two systems for deciding the stage of the
disease. One was developed by a surgeon named Dukes. It is
based on the growth of tumor through the layers of the colon,
invasion of nearby tissues, and spread to lymph nodes. The
staging system used most today is the Tumor, Nodes, Metastasis
These are the TNM stages for adenocarcinoma of the colon:
- Stage 0: cancer cells are only in the lamina propria (lining
layer), and have not invaded the outer layers or lymph nodes.
May be called, “carcinoma in situ.”
- Stage I: cancer has invaded from the lining layer into
the submucosa or as far as the muscle layer. Cancer has
not grown into any lymph nodes.
- Stage II: cancer has invaded the muscle layer, serosa,
and into nearby tissue, but has not spread to lymph nodes.
- Stage III: cancer has grown through all layers of the
intestine, into nearby tissues, and to a few nearby (regional)
lymph nodes. No tumor has traveled to distant nodes or organs.
- Stage IV: cancer has spread to other parts of the body
(liver, lungs, bones, brain), with or without lymph node
& Education Programs
We know that being diagnosed with cancer can be stressful for you and your
family. We offer a variety of cancer support services to help patients and
families gain the support and information they will need to meet the challenges
To find the Colon Cancer Support Group, other education workshops,
and wellness services offered this month, please view the
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