1. Colon cancer
Introduction
Cancer of the colon or rectum is also called colorectal cancer. In the United States, it is the fourth
most common cancer in men and women. Caught early, it is often curable.
It is more common in people over 50, and the risk increases with age. You are also more likely to
get it if you have
Polyps - growths inside the colon and rectum that may become cancerous
A diet that is high in fat
A family history or personal history of colorectal cancer
Ulcerative colitis or Crohn's disease
Over view
The human colon is a muscular, tube-shaped organ length about 4 feet long. It extends from the
end of your small bowel to your anus, twisting and turning through your abdomen (belly). The
colon has 3 main functions.
To digest and absorb nutrients from food
To concentrate fecal material by absorbing fluid (and electrolytes) from it
To store and control evacuation of fecal material
The right side of your colon plays a major role in absorbing water and electrolytes, while the left
side is responsible for storage and evacuation of stool.

2. Cancer is the transformation of normal cells. The transformed cells grow and multiply
abnormally.
Left untreated, these cancers grow and eventually spread through the colon wall to
including the adjacent lymph nodes and organs. Consequently, they spread to distant
organs such as the liver, lungs, brain, and bones.
Cancers are dangerous because of their unbridled growth. They overwhelm healthy cells,
tissues, and organs by taking their oxygen, nutrients, and space.
Most colon cancers are adenocarcinomas-tumors that develop from the glands lining the
colon's inner wall.
These tumors are sometimes referred to as colorectal cancer, reflecting the fact that the
rectum, the end portion of the colon, can also be affected.
In the United States, 1 in 17 people will develop colorectal cancer.
According to reports from the National Cancer Institute, colorectal cancer is the third
most common cancer in US men.
Colorectal cancer is the second most common cancer in US women of Hispanic,
American Indian/Alaska Native, or Asian/Pacific Islander ancestry, and the third most
common cancer in white and African American women.
The overall incidence of colorectal cancer increased until 1985 and then began decreasing
at an average rate of 1.6% per year.
Deaths from colorectal cancer rank third after lung and prostate cancer for men and third
after lung and breast cancer for women.

3. As mentioned above Colon, or colorectal, cancer is cancer that starts in the large intestine (colon)
or the rectum (end of the colon).
Other types of cancer can affect the colon, such as lymphoma, carcinoid tumors, melanoma, and
sarcomas. These are rare. In this article, use of the term "colon cancer" refers to colon carcinoma
only.
Causes
There would be many causes for this disease, According to the American Cancer Society,
colorectal cancer is one of the leading causes of cancer-related deaths in the United States.
However, early diagnosis can often lead to a complete cure.
Almost all colon cancer starts in glands in the lining of the colon and rectum. When doctors talk
about colorectal cancer, this is usually what they are talking about.
There is no single cause of colon cancer. Nearly all colon cancers begin as noncancerous
(benign) polyps, which slowly develop into cancer.
You have a higher risk for colon cancer if you:
Are older than 60
Are African American of eastern European descent
Eat a diet high in red or processed meats
Have cancer elsewhere in the body
Have colorectal polyps
Have inflammatory bowel disease (Crohn's disease or ulcerative colitis)

4. Have a family history of colon cancer
Have a personal history of breast cancer
Certain genetic syndromes also increase the risk of developing colon cancer. Two of the most
common are:
Familial adenomatous polyposis (FAP)
Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome
What you eat may play a role in your risk of colon cancer. Colon cancer may be associated with
a high-fat, low-fiber diet and red meat. However, some studies have found that the risk does not
drop if you switch to a high-fiber diet, so this link is not yet clear.
Smoking cigarettes and drinking alcohol are other risk factors for colorectal cancer.
Symptoms
Many cases of colon cancer have no symptoms. The following symptoms, however, may indicate
colon cancer:
Abdominal pain and tenderness in the lower abdomen
Blood in the stool
Diarrhea, constipation, or other change in bowel habits
Narrow stools
Weight loss with no known reason
Exams and Tests
With proper screening, colon cancer can be detected before symptoms develop, when it is most
curable.
There are 4 basic tests for colon cancer: a stool test (to check for blood); sigmoidoscopy
(inspection of the lower colon; colonoscopy (inspection of the entire colon); and double contrast
barium enema. All 4 are effective in catching cancers in the early stages, when treatment is most
beneficial. A rectal exam may reveal a mass in patients with rectal cancer, but not colon cancer.
A fecal occult blood test (FOBT) may detect small amounts of blood in the stool, which could
suggest colon cancer. However, this test is often negative in patients with colon cancer. For this
reason, a FOBT must be done along with colonoscopy or sigmoidoscopy. It is also important to
note that a positive FOBT doesn't necessarily mean you have cancer.
Imaging tests to screen for and potentially diagnose colorectal cancer include:
Colonoscopy

5. Sigmoidoscopy
Note: Only colonoscopy can see the entire colon, and this is the best screening test for colon
cancer.
Blood tests that may be done include:
Complete blood count (CBC) to check for anemia
Liver function tests
If your doctor learns that you do have colorectal cancer, more tests will be done to see if the
cancer has spread. This is called staging. CT or MRI scans of the abdomen, pelvic area, chest, or
brain may be used to stage the cancer. Sometimes, PET scans are also used.
Stages of colon cancer are:
Stage 0: Very early cancer on the innermost layer of the intestine
Stage I: Cancer is in the inner layers of the colon
Stage II: Cancer has spread through the muscle wall of the colon
Stage III: Cancer has spread to the lymph nodes
Stage IV: Cancer has spread to other organs

6. Blood tests to detect tumor markers, including carcinoembryonic antigen (CEA) and CA 19-9,
may help your physician follow you during and after treatment.
Treatment
Treatment depends on many things, including the stage of the cancer. In general, treatments may
include:
Surgery (most often a colectomy) to remove cancer cells
Chemotherapy to kill cancer cells
Radiation therapy to destroy cancerous tissue
SURGERY
Stage 0 colon cancer may be treated by removing the cancer cells, often during a colonoscopy.
For stages I, II, and III cancer, more extensive surgery is needed to remove the part of the colon
that is cancerous. (See: Colon resection)
CHEMOTHERAPY
Almost all patients with stage III colon cancer should receive chemotherapy after surgery for
approximately 6 - 8 months. This is called adjuvant chemotherapy. The chemotherapy drug 5-
fluorouracil has been shown to increase the chance of a cure in certain patients.
Chemotherapy is also used to improve symptoms and prolong survival in patients with stage IV
colon cancer.
Irinotecan, oxaliplatin, capecitabine, and 5-fluorouracil are the three most commonly
used drugs.

7. Monoclonal antibodies, including cetuximab (Erbitux), panitumumab (Vectibix),
bevacizumab (Avastin), and other drugs have been used alone or in combination with
chemotherapy.
You may receive just one type, or a combination of these drugs. There is some debate as to
whether patients with stage II colon cancer should receive chemotherapy after surgery. You
should discuss this with your oncologist.
RADIATION
Although radiation therapy is occasionally used in patients with colon cancer, it is usually used
in combination with chemotherapy for patients with stage III rectal cancer.
For patients with stage IV disease that has spread to the liver, various treatments directed
specifically at the liver can be used. This may include:
Burning the cancer (ablation)
Delivering chemotherapy or radiation directly into the liver
Freezing the cancer (cryotherapy)
Surgery
Outlook (Prognosis)
Colon cancer is, in many cases, a treatable disease if it is caught early.
How well you do depends on many things, especially the stage of the cancer. In general, when
treated at an early stage, many patients survive at least 5 years after their diagnosis. (This is
called the 5-year survival rate.)
If the colon cancer does not come back (recur) within 5 years, it is considered cured. Stage I, II,
and III cancers are considered potentially curable. In most cases, stage IV cancer is not
considered curable, although there are exceptions.
Possible Complications
Blockage of the colon
Cancer returning in the colon
Cancer spreading to other organs or tissues (metastasis)
Development of a second primary colorectal cancer
When to Contact a Medical Professional
Call your health care provider if you have:
Black, tar-like stools

8. Blood during a bowel movement
Change in bowel habits
Unexplained weight loss
Prevention
Although the death rate for colon cancer has dropped in the last 15 years. This may be due to
increased awareness and screening by colonoscopy.
Colon cancer can almost always be caught by colonoscopy in its earliest and most curable stages.
Almost all men and women age 50 and older should have a colon cancer screening. Patients at
risk may need earlier screening.
Colon cancer screening can often find polyps before they become cancerous. Removing these
polyps may prevent colon cancer.
For information, see:
Colon cancer screening
Colonoscopy
Changing your diet and lifestyle is important. Some evidence suggests that low-fat and high-fiber
diets may reduce your risk of colon cancer.
Some studies have reported that NSAIDs (aspirin, ibuprofen, naproxen, celecoxib) may help
reduce the risk of colorectal cancer. However, these medicines can increase your risk for
bleeding and heart problems. Most expert organizations do not recommend that most people take
these medicines to prevent colon cancer. Talk to your health care provider about this issue.

9. References
Burt RW, Barthel JS, Dunn KB, et al. NCCN clinical practice guidelines in oncology.
Colorectal cancer screening. J Natl Compr Canc Netw. 2010;8:8-61.
Cunningham D, Atkin W, Lenz HJ, Lynch HT, Minsky B, Nordlinger B, et al. Colorectal
cancer. Lancet. 2010;375:1030-1047.
Smith RA, Cokkinides V, Brooks D, Saslow D, Brawley OW. Cancer screening in the
United States, 2010: a review of current American Cancer Society guidelines and issues
in cancer screening. CA Cancer J Clin. 2010;60:99-119.