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Colon cancerIntroductionCancer of the colon or rectum is also called colorectal cancer. In the United States, it is the fourthmost 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 toget 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 Crohns diseaseOver viewThe human colon is a muscular, tube-shaped organ length about 4 feet long. It extends from theend of your small bowel to your anus, twisting and turning through your abdomen (belly). Thecolon 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 materialThe right side of your colon plays a major role in absorbing water and electrolytes, while the leftside is responsible for storage and evacuation of stool.
Cancer is the transformation of normal cells. The transformed cells grow and multiplyabnormally. 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 colons 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.
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, andsarcomas. These are rare. In this article, use of the term "colon cancer" refers to colon carcinomaonly.CausesThere 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 talkabout 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 (Crohns disease or ulcerative colitis)
Have a family history of colon cancer Have a personal history of breast cancerCertain genetic syndromes also increase the risk of developing colon cancer. Two of the mostcommon are: Familial adenomatous polyposis (FAP) Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndromeWhat you eat may play a role in your risk of colon cancer. Colon cancer may be associated witha high-fat, low-fiber diet and red meat. However, some studies have found that the risk does notdrop 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.SymptomsMany cases of colon cancer have no symptoms. The following symptoms, however, may indicatecolon 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 reasonExams and TestsWith proper screening, colon cancer can be detected before symptoms develop, when it is mostcurable.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 contrastbarium enema. All 4 are effective in catching cancers in the early stages, when treatment is mostbeneficial. 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 couldsuggest colon cancer. However, this test is often negative in patients with colon cancer. For thisreason, a FOBT must be done along with colonoscopy or sigmoidoscopy. It is also important tonote that a positive FOBT doesnt necessarily mean you have cancer.Imaging tests to screen for and potentially diagnose colorectal cancer include: Colonoscopy
SigmoidoscopyNote: Only colonoscopy can see the entire colon, and this is the best screening test for coloncancer.Blood tests that may be done include: Complete blood count (CBC) to check for anemia Liver function testsIf your doctor learns that you do have colorectal cancer, more tests will be done to see if thecancer has spread. This is called staging. CT or MRI scans of the abdomen, pelvic area, chest, orbrain 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
Blood tests to detect tumor markers, including carcinoembryonic antigen (CEA) and CA 19-9,may help your physician follow you during and after treatment.TreatmentTreatment depends on many things, including the stage of the cancer. In general, treatments mayinclude: Surgery (most often a colectomy) to remove cancer cells Chemotherapy to kill cancer cells Radiation therapy to destroy cancerous tissueSURGERYStage 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 colonthat is cancerous. (See: Colon resection)CHEMOTHERAPYAlmost all patients with stage III colon cancer should receive chemotherapy after surgery forapproximately 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 IVcolon cancer. Irinotecan, oxaliplatin, capecitabine, and 5-fluorouracil are the three most commonly used drugs.
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 towhether patients with stage II colon cancer should receive chemotherapy after surgery. Youshould discuss this with your oncologist.RADIATIONAlthough radiation therapy is occasionally used in patients with colon cancer, it is usually usedin combination with chemotherapy for patients with stage III rectal cancer.For patients with stage IV disease that has spread to the liver, various treatments directedspecifically 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) SurgeryOutlook (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, whentreated at an early stage, many patients survive at least 5 years after their diagnosis. (This iscalled 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 notconsidered 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 cancerWhen to Contact a Medical ProfessionalCall your health care provider if you have: Black, tar-like stools
Blood during a bowel movement Change in bowel habits Unexplained weight lossPreventionAlthough the death rate for colon cancer has dropped in the last 15 years. This may be due toincreased 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 atrisk may need earlier screening.Colon cancer screening can often find polyps before they become cancerous. Removing thesepolyps may prevent colon cancer.For information, see: Colon cancer screening ColonoscopyChanging your diet and lifestyle is important. Some evidence suggests that low-fat and high-fiberdiets may reduce your risk of colon cancer.Some studies have reported that NSAIDs (aspirin, ibuprofen, naproxen, celecoxib) may helpreduce the risk of colorectal cancer. However, these medicines can increase your risk forbleeding and heart problems. Most expert organizations do not recommend that most people takethese medicines to prevent colon cancer. Talk to your health care provider about this issue.
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.