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Anatomy of the Colon Helps to Define the Staging of the Disease
Colon cancer normally starts in the inner lining of the colon. This part is called the mucosa. As the cancer grows and progresses it grows towards the outside of the colon. The cancer starts making its way through the different layers of the colon wall which include the inner most thin muscle layer, a fibrous tissue, and another thick muscle layer which is important in passing the food through the colon. Finally the cancer spreads to the outer most layer of the colon which is made of connective tissue. If undetected or untreated it will grow through the colon wall. Eventually the cancer will spread to adjacent organs and to the lymph nodes. To determine treatment strategies, physicians need to know the extent at which the cancer has spread. As a result, the medical profession has developed a standard method by which they use to determine the severity of the disease.
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Staging Colon Cancer
Colon cancer survival rates are dependent on the class or stage at which the cancer is diagnosed. There are two known methods of classifying cancer progression.
Dukes Classification of colon cancer: This method uses the alphabetic Classes A, B and C to label the different extent of the disease. In class A the cancer is limited to the intestinal walls. Class B the cancer has spread beyond the bowels walls and a in Class C, the cancer has metastasized to other organs of the body.
The TMN system: This system is more precise. It uses the letter T to describe how far the primary tumor has grown through the colon walls. The N category describes the extent at which the cancer has spread to the lymph nodes. The N is linked with a numeric suffix that indicate how many lymph nodes the cancer has affected. The M stands for the metastatic level of the cancer.
Colon Cancer Stages
Stage I: The cancer is found in the walls of the colon at this stage. The survival rate is 80 to 95 percent or a 5 year survival rate in 93 percent of the cases.
Stage II: The cancer has spread beyond the colon's wall. Survival rates for this stage range from 55 to 88 percent (85 percent for IIA and 72 percent for IIB).
Stage III: The cancer can be found in the lymph nodes. At this stage the patient has a 40 percent chance of surviving the cancer with treatment (IIIA survival rate at 83 percent, IIIB 64 percent, and IIIC 44 percent)
Stage IV the cancer has spread to distant organs. The survival rate drops to 10 percent at this stage.
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Colon cancer treatment involves surgery, chemotherapy, or radiation. A doctor may recommend a combination treatment strategy depending on the severity of the disease. Treatment strategies can also affect the survival rates. If tumor removal is followed by chemotherapy in stages II, III and IV, then survival chances increase. Chances of survival are pretty high in stage I with surgery alone.
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