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Cancer |
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CANCER : Coloretal
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Colon cancer is cancer of the large intestine (colon) - the lower part of the digestive system. Rectal cancer is cancer of the last 6 inches of the colon. Together, they're often referred to as colorectal cancers. Most cases of colon cancer begin as small, non-cancerous (benign) clumps of cells called adenomatous polyps. Over time some of these polyps become colon cancers. Regular screening tests can help prevent colon cancer by identifying polyps before they become cancerous. |
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Risk factors |
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Factors that may increase your risk of colon cancer include: |
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| Age |
About 90 percent of people diagnosed with colon cancer are older than 50. Colon cancer can occur in younger people, but it occurs much less frequently.
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| A personal history of colorectal cancer or polyps |
If you've already had colon cancer or adenomatous polyps, you have a greater risk of colon cancer in the future.
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| Inflammatory intestinal conditions |
Long-standing inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease, can increase your risk of colon cancer.
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| Inherited disorders that affect the colon |
One genetic syndrome called familial adenomatous polyposis (FAP) is a rare disorder that causes you to develop thousands of polyps in the lining of colon and rectum. People with untreated FAP have a greater than 90 percent chance of developing colon cancer by age 45. Another genetic syndrome, hereditary nonpolyposis colorectal cancer (HNPCC), also called Lynch syndrome, is more common than FAP. People with HNPCC have an increased risk of colon cancer and tend to develop colon cancer at an early age. Both FAP and HNPCC can be detected through genetic testing.
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| Family history of colon cancer and colon polyps |
People are likely to develop colon cancer if they have a family history of disease. If more than one family member has colon cancer or rectal cancer, the risk is even greater.
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| Race |
In Singapore, Chinese have a higher risk of colon cancer than Malay or Indians.
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| Diet |
Colon cancer and rectal cancer may be associated with a diet low in fiber and high in fat and calories. Research in this area has had mixed results. Some studies have found an increased risk of colon cancer in people who eat diets high in red meat and processed meats.
When people move from a developing country to a Western country and adapt to the diet, their risk of colon cancer increases. Although many studies have tried to identify what part of the Western diet may cause colon cancer, the answer remains unknown.
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| A sedimentary lifestyle |
If somebody is inactive, he/she is more likely to develop colon cancer. Getting regular physical activity may reduce risk.
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| Diabetes |
People with diabetes and insulin resistance may have an increased risk of colon cancer.
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| Obesity |
People who are obese have an increased risk of colon cancer and an increased risk of dying of colon cancer when compared with people considered normal weight.
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| Smoking |
People who smoke cigarettes may have an increased risk of colon cancer.
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| Alcohol |
Heavy use of alcohol may increase risk of colon cancer. |
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Screening |
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Most colon cancers develop from adenomatous polyps. Screening can detect polyps before they become cancerous. Screening may also detect colon cancer in its early stages when there is a good chance for cure. |
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Stool blood test
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Stool DNA test |
This test involves analyzing several DNA markers, which come from cells that are shed by colon cancers or precancerous polyps into stool.
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Flexible sigmoidoscopy |
In this test, a flexible, slender and lighted tube is inserted to examine rectum and sigmoid — approximately the last 2 feet of your colon. The test usually takes just a few minutes.
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Barium enema |
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Colonoscopy |
Colonoscopy is similar to flexible sigmoidoscopy, but the instrument used — a colonoscope, which is a long, flexible and slender tube attached to a video camera and monitor — allows the doctor to view entire colon and rectum. If any polyps are found during the exam, the doctor may remove them immediately or take tissue samples (biopsies) for analysis. This is done through the colonoscope and is painless.
Virtual colonoscopy (CT colonography)may be one screening option. Virtual colonoscopy uses a computerized tomography (CT) machine to take images of colon, rather than using a scope inserted in the rectum to see inside the colon. |
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Diagnosis
- The diagnosis is usually confirmed by colonoscopy and biopsy.
- Besides certain tumour markers may be elevated, particularly CEA, CA 19.9
- PET CT Scan:
There is a lot of evidence for better staging of colorectal cancer using PET CT scan. It is also found to be helpful in monitoring therapy as well as for follow-up.
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Staging |
The stages of colon cancer are:
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| Stage 0 |
The cancer is in the earliest stage. It hasn't grown beyond the inner layer (mucosa) of the colon or rectum. This stage of cancer may also be called carcinoma in situ.
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| Stage I |
The cancer has grown through the mucosa but hasn't spread beyond the colon wall or rectum.
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| Stage II |
The cancer has grown into or through the wall of the colon or rectum but hasn't spread to nearby lymph nodes.
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| Stage III |
The cancer has invaded nearby lymph nodes but isn't affecting other parts of the body yet.
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| Stage IV |
The cancer has spread to distant sites, such as other organs — for instance to liver or lung, to the membrane lining the abdominal cavity, or to an ovary.
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| Recurrent. This means that the cancer has come back after treatment. It may recur in the colon, rectum or other part of the body. |
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Treatment |
The type of treatment depends largely on the stage of the cancer. The three primary treatment options are: surgery, chemotherapy and radiation. Your doctor will be the best person to discuss with you in detail.
Surgery (colectomy) is the main treatment for colorectal cancer. The extent of the colon removed and whether other therapies, such as radiation or chemotherapy, are an option, depends on the location and staging of the cancer. If cancer is small, localized in a polyp and in a very early stage, the surgeon may be able to remove it completely during a colonoscopy. Some larger polyps may be removed using laparoscopic surgery. In specific cases where the cancer has spread only to the liver, your doctor may recommend surgery to remove the cancerous lesion from the liver. Chemotherapy may be used before or after this type of surgery. This treatment may improve prognosis.
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Targeted drug therapy |
Three drugs that target specific defects that allow cancer cells to proliferate are available for patients with advanced colon cancer. The drugs bevacizumab (Avastin), cetuximab (Erbitux) and panitumumab (Vectibix) can be given along with chemotherapy drugs or alone. Bevacizumab works to prevent tumors from developing new blood vessels, which can deliver the oxygen and nutrients cancers need to survive. Cetuximab and panitumumab target a chemical signal that tells cells to divide and reproduce.
Cetuximab was approved by the Food and Drug Administration in 2007 as a single-agent treatment for advanced colon cancer for which other treatments have failed. Panitumumab remains experimental. Please discuss with your doctor for new treatment options. |
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