the Cancer Process
- The Colon and Rectum
- Colorectal Cancer
- Risk Factors
- Detecting Cancer Early
- Recognizing Symptoms
- Diagnosing Colorectal Cancer
- Orthodox Treatment
- Side Effects of Treatment
Understanding the Cancer Process
Cancer affects our cells, the body's basic unit of life.
To understand cancer, it is helpful to know what happens when
normal cells become cancerous. The body is made up of many
types of cells. Normally, cells grow, divide, and produce
more cells as they are needed to keep the body healthy and
functioning properly. Sometimes, however, the process goes
astray--cells keep dividing when new cells are not needed.
The mass of extra cells forms a growth or tumor. Tumors can
be either benign or malignant.
- Benign tumors are not cancer. They often can be removed
and, in most cases, they do not come back. Cells in benign
tumors do not spread to other parts of the body. Most important,
benign tumors are rarely a threat to life.
- Malignant tumors are cancer. Cells in malignant tumors
are abnormal and divide without control or order. These
cancer cells can invade and destroy the tissue around them.
Cancer cells can also break away from a malignant tumor.
They may enter the bloodstream or lymphatic system (the
tissues and organs that produce and store cells that fight
infection and disease). This process, called metastasis,
is how cancer spreads from the original (primary) tumor
to form new (secondary) tumors in other parts of the body.
The Colon and Rectum
The colon and rectum are parts of the body's digestive system,
which removes nutrients from food and stores waste until it
passes out of the body. Together, the colon and rectum form
a long, muscular tube called the large intestine (also called
the large bowel). The colon is the first 6 feet of the large
intestine, and the rectum is the last 8 to 10 inches.
Cancer that begins in the colon is called colon cancer, and
cancer that begins in the rectum is called rectal cancer.
Cancers affecting either of these organs may also be called
The exact causes of colorectal cancer are not known. However,
studies show that the following risk factors increase a person's
chances of developing colorectal cancer:
Having one or more of these risk factors does not guarantee
that a person will develop colorectal cancer. It just increases
- Age. Colorectal cancer is more likely to occur as people
get older. This disease is more common in people over the
age of 50. However, colorectal cancer can occur at younger
ages, even, in rare cases, in the teens.
， Diet. Colorectal cancer seems to be associated with diets
that are high in fat and calories and low in fiber. Researchers
are exploring how these and other dietary factors play a role
in the development of colorectal cancer.
， Polyps. Polyps are benign growths on the inner wall of the
colon and rectum. They are fairly common in people over age
50. Some types of polyps increase a person's risk of developing
A rare, inherited condition, called familial polyposis, causes
hundreds of polyps to form in the colon and rectum. Unless
this condition is treated, familial polyposis is almost certain
to lead to colorectal cancer.
， Personal medical history. Research shows that women with
a history of cancer of the ovary, uterus, or breast have a
somewhat increased chance of developing colorectal cancer.
Also, a person who has already had colorectal cancer may develop
this disease a second time.
， Family medical history. First-degree relatives (parents,
siblings, children) of a person who has had colorectal cancer
are somewhat more likely to develop this type of cancer themselves,
especially if the relative had the cancer at a young age.
If many family members have had colorectal cancer, the chances
increase even more.
， Ulcerative colitis. Ulcerative colitis is a condition in
which the lining of the colon becomes inflamed. Having this
condition increases a person's chance of developing colorectal
Detecting Cancer Early
People who have any of the risk factors described under "Colorectal
Cancer: Who's at Risk?" should ask a doctor when to begin
checking for colorectal cancer, what tests to have, and how
often to have them. The doctor may suggest one or more of
the tests listed below. These tests are used to detect polyps,
cancer, or other abnormalities, even when a person does not
have symptoms. Your health care provider can explain more
about each test.
- A fecal occult blood test (FOBT) is a test used to check
for hidden blood in the stool. Sometimes cancers or polyps
can bleed, and FOBT is used to detect small amounts of bleeding.
- A sigmoidoscopy is an examination of the rectum and lower
colon (sigmoid colon) using a lighted instrument called
- A colonoscopy is an examination of the rectum and entire
colon using a lighted instrument called a colonoscope.
- A double contrast barium enema (DCBE) is a series of x-rays
of the colon and rectum. The patient is given an enema with
a solution that contains barium, which outlines the colon
and rectum on the x-rays.
- A digital rectal exam (DRE) is an exam in which the doctor
inserts a lubricated, gloved finger into the rectum to feel
for abnormal areas.
Common signs and symptoms of colorectal cancer include:
These symptoms may be caused by colorectal cancer or by other
conditions. It is important to check with a doctor.
- A change in bowel habits
- Diarrhea, constipation, or feeling that the bowel does
not empty completely
- Blood (either bright red or very dark) in the stool
- Stools that are narrower than usual
- General abdominal discomfort (frequent gas pains, bloating,
fullness, and/or cramps)
- Weight loss with no known reason
- Constant tiredness
Diagnosing Colorectal Cancer
To help find the cause of symptoms, the doctor evaluates
a person's medical history. The doctor also performs a physical
exam and may order one or more diagnostic tests.
- X-rays of the large intestine, such as the DCBE, can reveal
polyps or other changes.
- A sigmoidoscopy lets the doctor see inside the rectum
and the lower colon and remove polyps or other abnormal
tissue for examination under a microscope.
- A colonoscopy lets the doctor see inside the rectum and
the entire colon and remove polyps or other abnormal tissue
for examination under a microscope.
- A polypectomy is the removal of a polyp during a sigmoidoscopy
- A biopsy is the removal of a tissue sample for examination
under a microscope by a pathologist to make a diagnosis.
If the diagnosis is cancer, the doctor needs to learn the
stage (or extent) of disease. Staging is a careful attempt
to find out whether the cancer has spread and, if so, to what
parts of the body. More tests may be performed to help determine
the stage. Knowing the stage of the disease helps the doctor
plan treatment. Listed below are descriptions of the various
stages of colorectal cancer.
- Stage 0. The cancer is very early. It is found only in
the innermost lining of the colon or rectum.
- Stage I. The cancer involves more of the inner wall of
the colon or rectum.
- Stage II. The cancer has spread outside the colon or rectum
to nearby tissue, but not to the lymph nodes. (Lymph nodes
are small, bean-shaped structures that are part of the body's
- Stage III. The cancer has spread to nearby lymph nodes,
but not to other parts of the body.
- Stage IV. The cancer has spread to other parts of the
body. Colorectal cancer tends to spread to the liver and/or
- Recurrent. Recurrent cancer means the cancer has come
back after treatment. The disease may recur in the colon
or rectum or in another part of the body.
Treatment depends mainly on the size, location, and extent
of the tumor, and on the patient's general health. Patients
are often treated by a team of specialists, which may include
a gastroenterologist, surgeon, medical oncologist, and radiation
oncologist. Several different types of treatment are used
to treat colorectal cancer. Sometimes different treatments
Research has led to many advances in the treatment of colorectal
cancer. Through research, doctors explore new ways to treat
cancer that may be more effective than the standard therapy.
- Surgery to remove the tumor is the most common treatment
for colorectal cancer. Generally, the surgeon removes the
tumor along with part of the healthy colon or rectum and
nearby lymph nodes. In most cases, the doctor is able to
reconnect the healthy portions of the colon or rectum. When
the surgeon cannot reconnect the healthy portions, a temporary
or permanent colostomy is necessary. Colostomy, a surgical
opening (stoma) through the wall of the abdomen into the
colon, provides a new path for waste material to leave the
body. After a colostomy, the patient wears a special bag
to collect body waste. Some patients need a temporary colostomy
to allow the lower colon or rectum to heal after surgery.
About 15 percent of colorectal cancer patients require a
- Chemotherapy is the use of anticancer drugs to kill cancer
cells. Chemotherapy may be given to destroy any cancerous
cells that may remain in the body after surgery, to control
tumor growth, or to relieve symptoms of the disease. Chemotherapy
is a systemic therapy, meaning that the drugs enter the
bloodstream and travel through the body. Most anticancer
drugs are given by injection directly into a vein (IV) or
by means of a catheter, a thin tube that is placed into
a large vein and remains there as long as it is needed.
Some anticancer drugs are given in the form of a pill.
- Radiation therapy, also called radiotherapy, involves
the use of high-energy x-rays to kill cancer cells. Radiation
therapy is a local therapy, meaning that it affects the
cancer cells only in the treated area. Most often it is
used in patients whose cancer is in the rectum. Doctors
may use radiation therapy before surgery (to shrink a tumor
so that it is easier to remove) or after surgery (to destroy
any cancer cells that remain in the treated area). Radiation
therapy is also used to relieve symptoms. The radiation
may come from a machine (external radiation) or from an
implant (a small container of radioactive material) placed
directly into or near the tumor (internal radiation). Some
patients have both kinds of radiation therapy.
- Biological therapy, also called immunotherapy, uses the
body's immune system to fight cancer. The immune system
finds cancer cells in the body and works to destroy them.
Biological therapies are used to repair, stimulate, or enhance
the immune system's natural anticancer function. Biological
therapy may be given after surgery, either alone or in combination
with chemotherapy or radiation treatment. Most biological
treatments are given by injection into a vein (IV).
- Clinical trials (research studies) to evaluate new ways
to treat cancer are an appropriate option for many patients
with colorectal cancer. In some studies, all patients receive
the new treatment. In others, doctors compare different
therapies by giving the promising new treatment to one group
of patients and the usual (standard) therapy to another
Side Effects of Treatment
The side effects of cancer treatment depend on the type of
treatment and may be different for each person. Most often
the side effects are temporary. Doctors and nurses can explain
the possible side effects of treatment. Patients should report
severe side effects to their doctor. Doctors can suggest ways
to help relieve symptoms that may occur during and after treatment.
- Surgery causes short-term pain and tenderness in the area
of the operation. Surgery for colorectal cancer may also
cause temporary constipation or diarrhea. Patients who have
a colostomy may have irritation of the skin around the stoma.
The doctor, nurse, or enterostomal therapist can teach the
patient how to clean the area and prevent irritation and
- Chemotherapy affects normal as well as cancer cells. Side
effects depend largely on the specific drugs and the dose
(amount of drug given). Common side effects of chemotherapy
include nausea and vomiting, hair loss, mouth sores, diarrhea,
and fatigue. Less often, serious side effects may occur,
such as infection or bleeding.
- Radiation therapy, like chemotherapy, affects normal as
well as cancer cells. Side effects of radiation therapy
depend mainly on the treatment dose and the part of the
body that is treated. Common side effects of radiation therapy
are fatigue, skin changes at the site where the treatment
is given, loss of appetite, nausea, and diarrhea. Sometimes,
radiation therapy can cause bleeding through the rectum
- Biological therapy may cause side effects that vary with
the specific type of treatment. Often, treatments cause
flu-like symptoms, such as chills, fever, weakness, and