Did you know!!
Colon cancer happens when tumorous growths develop in the large intestine. It is the third most common type of cancer in the United States.
The colon, or large intestine, is
where the body extracts water and salt from solid wastes. The waste then moves
through the rectum and exits the body through the anus.
Regular screenings are recommended
after the age of 50 years.
Colon cancer
and rectal cancer may occur together. This is called colorectal cancer. Rectal cancer originates in the rectum, which is the last
several inches of the large intestine, closest to the anus.
Fast facts on colon cancer:
Here are some key points about colon
cancer.
Ø Colon cancer affects the large intestine and it usually
starts with polyps in the wall of the intestine.
Ø Symptoms may not appear until a later stage, but if they do,
gastrointestinal problems are common symptoms.
Ø Treatment involves a combination of chemotherapy, radiationtherapy, and surgery, possibly resulting in a colostomy.
Ø A healthy lifestyle with a high-fiber, low-fat diet can help
prevent colon cancer, and screening can detect it in the early stages.
Symptoms
and signs
Colon cancer affects the large intestine. It usually
develops from benign polyps.
There are often no symptoms in the
earliest stages, but symptoms may develop as the cancer advances.
They include:
Ø diarrhea or constipation
Ø changes in stool consistency
Ø loose and narrow stools
Ø rectal bleeding or blood in the stool
Ø abdominal pain, cramps, bloating, or gas
Ø pain during bowel movements
Ø continual urges to defecate
Ø weakness and fatigue
Ø unexplained weight loss
Ø irritablebowelsyndrome (IBS)
Ø iron deficiency anemia
If the cancer spreads to a new
location in the body, additional symptoms can appear in the new area. The liver
is most commonly affected.
Stages
There are different ways of staging
cancer. The stages depend on how far the cancer has spread.
Stage 0: The cancer is in a very early stage. It is known as carcinoma in situ. It has not grown further than the inner layer of
the colon.
Stage 1: The cancer has grown into the next layer of tissue, but it
has not reached the lymph nodes or other organs.
Stage 2: The cancer has reached the outer layers of the colon, but
it has not spread beyond the colon.
Stage 3: The cancer has grown through outer layers of the colon and
it has reached one to three lymph nodes. It has not spread to distant sites.
Stage 4: The cancer has reached other tissues beyond the wall of
the colon. As stage 4 progresses, the cancer reaches distant parts of the body.
Cancer develops progressively. Each
stage is not fixed but describes a phase during which certain developments take
place.
Managment
Treatment will depend on the type
and stage of the cancer, and the age, health status, and other characteristics
of the patient.
There is no single treatment for any
cancer, but the most common options for colon cancer are surgery, chemotherapy,
and radiation therapy.
Treatments seek to remove the cancer
and relieve any painful symptoms.
Surgery
Surgery for colorectal cancer often means a person will need
a colostomy. A bag collects waste from a stoma, bypassing the need for the
lower part of the large intestine.
Surgery to remove part or all of the
colon is called a colectomy. The surgeon removes the part of the colon
containing the cancer and the surrounding area.
Nearby lymph nodes are also usually
removed. The healthy portion of the colon will either be reattached to the
rectum or attached to a stoma depending on the extent of the colectomy.
A stoma is an opening made in the
wall of the abdomen. Waste will pass into a bag, removing the need for the
lower part of the colon. This is called a colostomy.
Some small, localized cancers can be
removed using endoscopy.
Laparoscopic surgery, using several
small incisions in the abdomen, may be an option to remove larger polyps.
Palliative surgery may relieve
symptoms in cases of untreatable or advanced cancers. The aim is to relieve any
blockage of the colon and manage pain, bleeding, and other symptoms.
Chemotherapy
Chemotherapy administers chemicals
that interfere with the cell division process by damaging proteins or DNA in
order to damage and kill cancer cells.
These treatments target any rapidly
dividing cells, including healthy ones. The healthy cells can usually recover
from any chemically-induced damage, but cancer cells cannot.
Chemotherapy is generally used to
treat cancer that has spread because the medicines travel through the whole
body. Treatment occurs in cycles, so the body has time to heal between doses.
Common side effects include:
Ø Â
Combination therapies often mix
multiple types of chemotherapy or combine chemotherapy with other treatments.
Radiation
Radiation treatment damages and
kills cancer cells by focusing high-energy gamma-rays on them.
Radioactive gamma-rays are emitted
from metals such as radium, or from high-energy x-rays. Radiotherapy can be
used as a standalone treatment to shrink a tumor or
destroy cancer cells, or alongside other cancer treatments.
Radiation treatments are not often
used until a later stage. They may be employed if early stage rectal cancer has
penetrated the wall of the rectum or traveled to nearby lymph nodes.
Side effects may include:
Ø mild skin changes resembling sunburn or suntan
Ø nausea
Ø vomiting
Ø diarrhea
Ø fatigue
Ø appetite and weight loss
Most side effects resolve a few
weeks after completing treatment.
Prevention
Standard preventive measures
include:
Ø maintaining a healthy weight
Ø exercising
Ø consuming plenty of fruits, vegetables, and whole grains
Ø decreasing saturated fat and red meat intake
People are also recommended to limit
alcohol consumption and quitsmoking.
Some
causes
Normally, body cells follow an
orderly process of growth, division, and death. Cancer happens when cells grow
and divide uncontrollably, without dying.
Most colon cancer originates from
noncancerous, or benign, tumors called adenomatous polyps that form on the
inner walls of the large intestine.
Cancerous cells may spread from
malignant tumors to other parts of the body through the blood and lymph
systems.
These cancer cells can grow and
invade healthy tissue nearby and throughout the body, in a process called
metastasis. The result is a more serious, less treatable condition.
The exact causes are unknown, but
colon cancer has several potential risk factors.
Polyps
Colon cancer usually derives from
precancerous polyps that exist in the large intestine.
The most common types
of polyps are:
- Adenomas: These can resemble the normal lining of the colon but look different under a microscope. They can become cancerous.
- Â Hyperplastic polyps: Colon cancer rarely develops from hyperplastic polyps, as they are typically benign.
Some of these polyps may grow into
malignant colon cancer over time, if they are not removed during the early
stages of treatment.
Genes
Uncontrolled cell growth can happen
if there is genetic damage, or if changes to the DNA affect cell division. A
genetic predisposition can be inherited from family members, but most colon
cancers occur in people without a family history.
Some people are born with certain
genetic mutations that make them statistically more likely to develop cancer
later in life. Sometimes, a person will have this genetic feature, but cancer
will not develop unless an environmental factor triggers it.
Traits,
habits, and diet
Age is an important risk factor for
colon cancer. Around 91 percent
of those who receive a diagnosis are over 50 years old.
Colon cancer is morelikely
in people with sedentary lifestyles, those with obesity, and those who smoke tobacco.
As the colon is part of the
digestive system, diet is an important factor. Diets that are low in fiber and
high in fat, calories, red meat, alcohol, and processed meats have been linked to
a higher risk
of colon cancer.
Underlying
conditions
Some conditions and treatments have
been associated with an increased risk of colon cancer.
These include:
Ø diabetes
Ø acromegaly, a growth hormone disorder
Ø radiation treatment for other cancers
Ø inflammatory bowel disease, such as ulcerative colitis or Crohn's disease
Diagnosis
A physician will carry out a
complete physical exam and ask about personal and family medical histories.
Diagnosis is usually made
after colonoscopy or a barium enema x-ray.
Colonoscopy
A long, flexible tube with a camera
on one end is inserted into the rectum to inspect the inside of the colon.
The patient may have to follow a
special diet for 24 to 48 hours before the procedure. The colon will also
require cleansing with strong laxatives, a process known as bowel prep.
If polyps are found in the colon,
they are removed and sent to a pathologist for biopsy, an examination under a
microscope that detects cancerous or precancerous cells.
A similar procedure, called a
flexible sigmoidoscopy, examines a smaller portion of the colorectal area. This
involves less preparation, and a full colonoscopy may not be needed if polyps
are not found, or if they are located within a small area.
Double-contrast
barium enema
This x-ray procedure uses a liquid
called barium to provide clearer imaging results than a standard x-ray can
give. Before a barium enema, the patient must fast for several hours.
A liquid solution containing the
element barium is then injected into the colon through the rectum, followed by
a brief pumping of air to smooth over barium layer for optimal results.
The x-ray of the colon and rectum is
then taken. The barium will appear white on the x-ray, and tumors and polyps
will appear as dark outlines.
If a biopsy suggests colon cancer,
the doctor may order a chest x-ray, ultrasound, or CT scan of the lungs, liver, and abdomen to assess the spread of
the cancer.
There may also be a blood test for a
substance produced by some cancer cells called carcinoembryonic antigen (CEA).
Following a diagnosis, the doctor
will determine the stage of the cancer based on the size and extent of the
tumor, and on the spread to nearby lymph nodes and distant organs.
A cancer's stage will determine the
treatment options and inform the prognosis, or the likely course the cancer
will take.
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