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Colon Cancer Treatment & Prevention
By peace | December 23, 2006
Colon cancer remains a major cause of death and disease, especially in the Western world. A clear understanding of the causes and course of the disease is emerging. This has allowed for recommendations regarding screening for and prevention of this disease. The removal of colon polyps helps prevent colon cancer. Early detection of colon cancer can improve the chances of a cure and overall survival. Treatment remains unsatisfactory for advanced disease, but research in this area remains strong and newer treatments continue to emerge. New and exciting preventive measures have recently focused on the possible beneficial effects of aspirin or other anti-inflammatory agents. In trials, the use of these agents has markedly limited colon cancer formation in several experimental models. Other agents being evaluated to prevent colon cancer include calcium, selenium, and vitamins A, C, and E. More studies are needed before these agents can be recommended for widespread use by the public to prevent colon cancer.
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 colonoscope 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 colonoscopes 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.
Sometimes, the doctor may obtain a blood test for CEA (carcinoembyonic antigen). CEA is a substance produced by some cancer cells. It is sometimes found in high levels in patients with colorectal cancer, especially when the disease has spread.
There are different types of treatment for patients with colon cancer.
Different types of treatment are available for patients with colon cancer. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. Before starting treatment, patients may want to think about taking part in a clinical trial. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.
Clinical trials are taking place in many parts of the country. Choosing the most appropriate cancer treatment is a decision that ideally involves the patient, family, and health care team.
Three types of standard treatment are used. These include the following:
1. Surgery
Surgery (removing the cancer in an operation) is the most common treatment for all stages of colon cancer. A doctor may remove the cancer using one of the following types of surgery:
- Local excision: If the cancer is found at a very early stage, the doctor may remove it without cutting through the abdominal wall. Instead, the doctor may put a tube through the rectum into the colon and cut the cancer out. This is called a local excision. If the cancer is found in a polyp (a small bulging piece of tissue), the operation is called a polypectomy.
- Resection: If the cancer is larger, the doctor will perform a partial colectomy (removing the cancer and a small amount of healthy tissue around it). The doctor may then perform an anastomosis (sewing the healthy parts of the colon together). The doctor will also usually remove lymph nodes near the colon and examine them under a microscope to see whether they contain cancer.
- Resection and colostomy: If the doctor is not able to sew the 2 ends of the colon back together, a stoma (an opening) is made on the outside of the body for waste to pass through. This procedure is called a colostomy. A bag is placed around the stoma to collect the waste. Sometimes the colostomy is needed only until the lower colon has healed, and then it can be reversed. If the doctor needs to remove the entire lower colon, however, the colostomy may be permanent. Three panel drawing showing colon cancer surgery with colostomy; first panel shows area of colon with cancer, middle panel shows cancer and nearby tissue removed and stoma created, last panel shows a colostomy bag attached to the stoma.
- Radiofrequency ablation: The use of a special probe with tiny electrodes that kill cancer cells. Sometimes the probe is inserted directly through the skin and only local anesthesia is needed. In other cases, the probe is inserted through an incision in the abdomen. This is done in the hospital with general anesthesia.
- Cryosurgery: A treatment that uses an instrument to freeze and destroy abnormal tissue, such as carcinoma in situ. This type of treatment is also called cryotherapy.
Even if the doctor removes all the cancer that can be seen at the time of the operation, some patients may be given chemotherapy or radiation therapy after surgery to kill any cancer cells that are left. Treatment given after the surgery, to increase the chances of a cure, is called adjuvant therapy.
2. Chemotherapy
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the spinal column, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy).
Chemoembolization of the hepatic artery may be used to treat cancer that has spread to the liver. This involves blocking the hepatic artery (the main artery that supplies blood to the liver) and injecting anticancer drugs between the blockage and the liver. The liver’s arteries then deliver the drugs throughout the liver. Only a small amount of the drug reaches other parts of the body. The blockage may be temporary or permanent, depending on what is used to block the artery. The liver continues to receive some blood from the hepatic portal vein, which carries blood from the stomach and intestine.
The way the chemotherapy is given depends on the type and stage of the cancer being treated.
3. Radiation therapy
Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated.
Other types of treatment are being tested in clinical trials. These include the following:
- Biologic therapy – Biologic therapy is a treatment that uses the patient’s immune system to fight cancer. Substances made by the body or made in a laboratory are used to boost, direct, or restore the body’s natural defenses against cancer. This type of cancer treatment is also called biotherapy or immunotherapy.
Follow-up exams may help find recurrent colon cancer earlier.
After treatment, a blood test to measure carcinoembryonic antigen (CEA; a substance in the blood that may be increased when colon cancer is present) may be done along with other tests to see if the cancer has come back.
Patients whose colon cancer spreads or recurs after initial treatment with chemotherapy may be offered further chemotherapy with a different drug or combination of drugs.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) depends on the following:
* The stage of the cancer (whether the cancer is in the inner lining of the colon only, involves the whole colon, or has spread to other places in the body).
* Whether the cancer has blocked or created a hole in the colon.
* The blood levels of carcinoembryonic antigen (CEA; a substance in the blood that may be increased when cancer is present) before treatment begins.
* Whether the cancer has recurred.
* The patient’s general health.
Prevention
People can change their eating habits by reducing fat intake, and increasing fiber (roughage) in their diet. Major sources of fat are meat, eggs, dairy products, salad dressings, and oils used in cooking. Fiber is the insoluble, non- digestible part of plant material present in fruits, vegetables, and whole-grain breads and cereals. It is postulated that high fiber in the diet leads to the creation of bulky stools which can rid the intestines of potential carcinogens. In addition, fiber leads to the more rapid transit of fecal material through the intestine, thus allowing less time for a potential carcinogen to react with the intestinal lining.
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.
Topics: All Posts, Diseases, Man's health, Woman's Health | 1 Comment »
July 24th, 2007 at 3:21 pm
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