Colon cancer forms in the longest part of the large intestine. Most colon cancers are adenocarcinomas. Rectal cancers form in the tissues of the rectum, which include the last several inches of the large intestine closest to the anus. Colorectal cancers are the third most common cancer in the United State. Colorectal cancer accounts for eleven percent of all cancers and is the cause of ten percent of all cancer deaths. This type of cancer is equally distributed between men and women, but has an increased incidence in those over the age of fifty years. The incidence rate is fifty times higher for those in 60-79 years of age as compared to those aged 40. African Americans, Hawaiians and Mexicans have a higher incidence rate of obtaining colorectal cancer.
In regards to the etiology of colorectal cancer, the cause is unknown. Research indicates that diet, age, genetics and environment play a causative role. Predisposing factors such as bowel disorders may play a role as well. Bowel disorders that may be predisposing factors could include: ulcerative colitis, Crohn’s disease, polyposis, and inflammatory bowel disorder. There are several screenings that may help detect colorectal cancer. These screening tests may include an annual fecal blood test for those over the age of fifty, a colonoscopy every ten years, and a proctosigmoidoscopy every five years.
Symptoms for colorectal cancer can vary according to the tumor type, size, location and individual. Depending on what side the lesions are present, different symptoms will appear. Symptoms may involve change in bowl habits, blood in stool, abdominal pain, anorexia, and indigestion. The staging is based on the degree of depth of tumor involvement and presence of nodes. The staging system came from the Duke’s classification system but is still TNM. Colorectal metastasis can spread by direction extension into the layers of the bowel. The most common sites for the cancer to spread are the liver, lung, brain and...
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