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We hope that you’ll find this information about Colon Cancer helpful and that you’ll seek professional medical advice to address any specific symptoms you might have related to this matter.
The colon is the part of the digestive system where the waste material is stored. The rectum is the end of the colon adjacent to the anus. Together, they form a long, muscular tube called the large intestine (also known as the large bowel). Tumors of the colon and rectum are growths arising from the inner wall of the large intestine. Benign tumors of the large intestine are called polyps. Malignant tumors of the large intestine are called cancers. Benign polyps do not invade nearby tissue or spread to other parts of the body. Benign polyps can be easily removed during colonoscopy, and are not life threatening. If benign polyps are not removed from the large intestine, they can become malignant (cancerous) over time. Most of the cancers of the large intestine are believed to have developed from polyps. Cancer of the colon and rectum (also referred to as colorectal cancer) can invade and damage adjacent tissues and organs. Cancer cells can also break away and spread to other parts of the body (such as liver and lung) where new tumors form. The spread of colon cancer to distant organs is called metastasis of the colon cancer. Once metastasis has occurred in colorectal cancer, a complete cure of the cancer is unlikely.
What are the causes colon cancer? (top)
Doctors are certain that colorectal cancer is not contagious (a person cannot catch the disease from a cancer patient). Some people are more likely to develop colorectal cancer than others. Factors that increase a person’s risk of colorectal cancer include high fat intake, a family history of colorectal cancer and polyps, the presence of polyps in the large intestine, and chronic ulcerative colitis.
What are the symptoms of colon cancer? (top)
Symptoms of colon cancer are numerous and non-specific. They include fatigue, weakness, shortness of breath, change in bowel habits, narrow stools, diarrhea or constipation, red or dark blood in stool, weight loss, abdominal pain, cramps, or bloating. Other conditions such as irritable bowel syndrome (spastic colon), ulcerative colitis, Crohn’s disease, diverticulosis, and peptic ulcer disease can have symptoms that mimic colorectal cancer.
How is colon cancer diagnosed? (top)
When colon cancer is suspected, either a lower GI series (barium enema x-ray) or colonoscopy is performed to confirm the diagnosis and to localize the tumor.
A barium enema involves taking x-rays of the colon and the rectum after the patient is given an enema with a white, chalky liquid containing barium. The barium outlines the large intestines on the x-rays. Tumors and other abnormalities appear as dark shadows on the x-rays.
Colonoscopy is a procedure whereby a doctor inserts a long, flexible viewing tube into the rectum for the purpose of inspecting the inside of the entire colon. Colonoscopy is generally considered more accurate than barium enema x-rays, especially in detecting small polyps. If colon polyps are found, they are usually removed through the colonoscopy and sent to the pathologist. The pathologist examines the polyps under the microscope to check for cancer. While the majority of the polyps removed through the colonoscopies are benign, many are precancerous. Removal of precancerous polyps prevents the future development of colon cancer from these polyps.
If cancerous growths are found during colonoscopy, small tissue samples (biopsies) can be obtained and examined under the microscope to confirm the diagnosis. If colon cancer is confirmed by a biopsy, staging examinations are performed to determine whether the cancer has already spread to other organs. Since colorectal cancer tends to spread to the lungs and the liver, staging tests usually include chest x-rays, ultrasonography, or a CAT scan of the lungs, liver, and abdomen.
How can colon cancer be prevented? (top)
Unfortunately, colon cancers can be well advanced before they are detected. The most effective prevention of colon cancer is early detection and removal of precancerous colon polyps before they turn cancerous. Even in cases where cancer has already developed, early detection still significantly improves the chances of a cure by surgically removing the cancer before the disease spreads to other organs. Multiple world health organizations have suggested general screening guidelines.
What are the treatments and survival for colon cancer? (top)
Surgery is the most common treatment for colorectal cancer. During surgery, the tumor, a small margin of the surrounding healthy bowel, and adjacent lymph nodes are removed. The surgeon then reconnects the healthy sections of the bowel. In patients with rectal cancer, the rectum is permanently removed. The surgeon then creates an opening (colostomy) on the abdomen wall through which solid waste in the colon is excreted. Specially trained nurses (enterostomal therapists) can help patients adjust to colostomies, and most patients with colostomies return to a normal lifestyle.
The long term prognosis after surgery depends on whether the cancer has spread to other organs (metastasis). The risk of metastasis is proportional to the depth of penetration of the cancer into the bowel wall. In patients with early colon cancer which is limited to the superficial layer of the bowel wall, surgery is often the only treatment needed. These patients can experience long term survival in excess of eighty percent. In patients with advanced colon cancer, wherein the tumor has penetrated beyond the bowel wall and there is evidence of metastasis to distant organs, the five year survival rate is less than ten percent.
In some patients, there is no evidence of distant metastasis at the time of surgery, but the cancer has penetrated deeply into the colon wall, or reached adjacent lymph nodes. These patients are at risk of tumor recurrence either locally or in distant organs. Chemotherapy in these patients may delay tumor recurrence and improve survival.