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Colon Cancer- veggies versus meat
Cancer of the colon is second most common cause of death in North America. Data from the cancer registry indicate that about 150,000 Americans are diagnosed each year with colon cancer and about 50% die from the disease. Current estimates indicate that approximately one in 17 individuals will develop colorectal cancer at some point in their life. No race is immune from colon cancer, but blacks have a slightly higher rates compared to other ethnic groups Much of the current evidence to today indicates that early detection and screening tests for colorectal cancer can reduce the number of cancer related deaths. It is recommended by the various agencies that colon cancer screening should be initiated by the 5th decade of life. In those with risk factors for colon cancer, the screening should be started in the 4th decade of life. Advances in genetic research have provided clues to familial colon cancers and these individuals are being urged to have early endoscopic or genetic screening much early in life However, screening for the entire population for colon cancer has been associated with a lot of controversy. The U.S. Preventive Services Task Force (USPSTF) has recommended screening with fecal occult blood testing and sigmoidoscopy for asymptomatic persons at average risk for colorectal cancer. Despite all these recommendations, there is a lack of scientific data to suggest if these screening procedures will be of any benefit. Even the frequency of screening is hotly debated.
How colon cancer begins Colon cancer typically begins early on as a polyp somewhere in the colon. The term polyp is defined as a small ballooning or protuberance of colonic tissue into the colonic lumen. There are many types of polyps but it is the adenomatous polyps which are precancerous. The risk of cancer of a poly is dependent on the size and degree of changes in the polyp. Current evidence indicates that it takes about 10 years for a poly to become a full blown cancer. Rough estimates indicate that nearly 40% of Americans older than 50 years have a poly and of these at least 2% are expected to progress into cancer at some point in their lives. Because all polyps look alike upon visualization, it is essential that they be removed and looked under a microscope to ensure that they have no cancerous features.
Risk factors associated with colon cancer Environmental factors that have been linked to colon cancer include: - advanced age - fatty diet - smoking - alcohol consumption - obesity - diet high in meat - lack of fiber in diet Despite all the talk about these environmental factors, more than 70% of individuals who develop colon cancer do not have any of the above risk factors.
Other Risk Factors for Colorectal Cancer - past history of polyps or colon cancer - First-degree relative age < 60 yrs with colon cancer - two first-degree relatives of any age with colorectal cancer - Inherited colorectal cancer syndromes - Hereditary nonpolyposis colorectal cancer - Familial adenomatous polyposis - Ulcerative colitis and Cohn’s colitis A personal history of adenomatous polyps or colon cancer is also known to increase the risk of multiple sites for colon cancer. Patients with the highest risk for colorectal cancer are those who have one of the dominantly inherited colorectal cancer syndromes:
Familial syndromes associated with colon cancer There are some rare syndromes which cause colon cancer in families. These familial syndromes are associated with hundreds of small polyps which predispose the individual to colon cancer. Colon cancers typically develop in these individual by the age of 40. To prevent colon cancer, the entire colon must be removed. Most of these syndromes of polyposis also disorders of other organs.
Inflammatory bowel disease The chronic inflammatory disorders such as ulcerative colitis and Crohn's disease are associated with an increased risk of colorectal cancer. The risk of colon cancer increases with the duration of the inflammatory bowel disease. Both groups of patients need close surveillance and frequent colonoscopy. After a decade of disease, the cancer risk increases yearly by 1% to 2%.
Signs and Symptoms Small polyps and early colon cancers produce no symptoms. The majority of individual only have symptoms when the polyps are large or cause bleeding in the rectum. Other symptoms that may be indicative of a problem is blood in the stools, anemia or a general feeling of malaise. When the tumor gets larger, the individual may start to develop abdominal cramps, weight loss, nausea, vomiting or anorexia and a change in bowel habits.
Diagnosis The diagnosis of colon cancer is most often made during a colonic evaluation performed for one of the above complaints, colorectal cancer screening, or as part of endoscopic surveillance.
Current Screening Recommendations In the past decade, many groups, including the American Cancer Society, the United States Preventive Service Task Force, and various physician associations have established guidelines for colon cancer screening and surveillance. These Panels have recommended that, beginning at the age of 50 years; individuals with an average risk for colorectal cancer should undergo one of the following screening tests: 1. Fecal occult blood testing annually. 2. Flexible sigmoidoscopy every five years. 3. Fecal occult blood testing annually and flexible sigmoidoscopy every five years. 4. Double-contrast barium enema every five to 10 years. 5. Colonoscopy every 10 years. Although all of these screening strategies are acceptable options, each strategy has unique strengths and weaknesses.
Fecal blood testing The fecal occult blood test is a nonspecific test that fails to detect many small cancers and precancerous lesions. Nonetheless, few studies have shown that annual detection of blood in the stools can reduces the number of deaths caused by colon cancer. The test involves collecting stools and testing them for blood. All individuals should be informed not to take any aspirin, red meat, Vitamin C, turnips or horseradish for at least 2-4 days before the test. Any positive blood test must be evaluated by either sigmoidoscopy or colonoscopy. A major drawback to fecal occult blood testing as a screening technique is that many individuals just do not show up for the test. Collecting poop in a small container is not a fun pastime for most people. Most studies have indicated that less than 30% of individuals ever show up for the test. For those who are unable to collect the stools, the physician inserts a gloved finger in the rectum and the glove is tested for blood- another great medical exam which is not fun for most people. Doctors recommend that stool testing should be combined with a sigmoidoscopy every 5 years.
Sigmoidoscopy The effectiveness of sigmoidoscopy as a screening tool depends on where the cancer is located. Sigmoidoscopy only evaluates the distal part of the colon (about 30-45 cm). At least 50% of polyps and cancers are beyond the limits of detection of the longest (e.g., 60 cm) flexible sigmoidoscopy. If the sigmoidoscopy examination detects polyps, colonoscopy should be strongly considered because almost one third of such patients have another cancerous lesion in the proximal colon. A few studies have shown that regular screening with this test is of some benefit.
Barium enema The efficacy of barium enema in preventing deaths from colorectal cancer has not been fully studied. Barium enema can help evaluated the entire colon. However, the study is not very sensitive and can miss small polyps. It is not a good screening test and can miss early cancers. Barium enema generally can detect large polyps (about 1 cm) and is it assumed that it may also have a beneficial effect. However, a number of studies have reported that polyps the size of 1 cm are missed 50% of the time. Barium enema also is known to miss many masses in the lower colon because of the overlapping folds of the bowel. Physicians recommend that barium enema should be combined with sigmoidoscopy to be more effective in screening for cancers of the colon. The major limitation of barium enema as a screening method is that patients require colonoscopy if lesions are detected.
Colonoscopy Colonoscopy is the only screening technique that allows the detection and removal of premalignant lesions throughout the colon and rectum. Furthermore, it is the ultimate test and one can also obtain a biopsy and a diagnosis of cancer can be confirmed. Many studies have documented that colonoscopy can identify early polyps and leads to early detection of cancers. The test is easier to perform and only requires cleansing of the bowel with laxative the day before. The procedure however, does require some IV sedation. The procedure can safely be done in about 95% of individuals.
Savings? The Office of Technology Assessment of the U.S. Congress found that fecal occult blood testing, sigmoidoscopy, double-contrast enema and colonoscopy are about equally cost-effective as screening strategies, with an estimated cost of less than $20,000 per year of life saved (assuming that screening begins at the age of 50 years and is discontinued at the age of 85 years).
Medical Coverage For the past 10 years, Medicare has covered colorectal cancer screening in persons at average risk for this malignancy who are over 50 years of age. Medicare does not reimburse the cost of screening colonoscopy in persons at average risk, but it does cover annual fecal occult blood testing as well as flexible sigmoidoscopy or barium enema performed every four years. Reimbursement by other third-party payors is variable. Unfortunately, not all Americans under the age of 65 have health care benefits that would cover the charges for colonoscopy which may impact on patient compliance with screening colonoscopy.
Treatment The prognosis of colorectal cancer is based on the staging of the cancer. The depth of tumor invasion and lymph node involvement are the two major components constituting the basis for colon cancer staging. The primary treatment of colon cancer is surgical resection of the primary tumor and regional lymph nodes. Surgery is curative for most early-stage colon tumors. For more advanced stages, surgery and adjuvant therapy are recommended to prevent recurrence and prolong survival.
Adjuvant Treatment All studies reveal that adjuvant therapy is of benefit to patients with colon cancer. For those individual who have stage 2 colon cancer, adjuvant therapy increases disease free survival, but does not always prolong life.
Clinical trials In the last decade, numerous trials have revealed that improvements in surgery techniques may help remove all the cancer and decrease the recurrence of colon cancer. In addition, to surgery, routine use of radiation therapy has also helped to decrease the recurrence rates of colon cancer. Whether to give radiation before or after the surgery has not been fully studied. Unfortunately, despite these advances, the survival rates still remain abysmal. Outside of clinical trials, curative-intent surgery combined with radio chemotherapy remains the recommended standard for treatment of stage II and III colon cancer.
Can we prevent Colon Cancer? Over the past 2 decades, numerous epidemiologic studies have found a modest decrease in colorectal cancer in patients who regular take nonsteroidal anti-inflammatory drugs, particularly aspirin, calcium and folate. Unfortunately, randomized controlled trials of the use of such agents, herbs, nutrients are limited. The effectiveness and cost-effectiveness of over the counter agents for prevention of colon cancer is a billion dollar industry and there are daily claims of cancer cure. However, most of these herbs, spices, nutrients are considered junk and have even less value than drinking one’s urine. There are no scientific data to back up the claims by these nutritionists.
Prognosis The prognosis of colon cancer is highly dependent on the stage and the actual pathology results obtained after surgery are the most important. - If colon cancer is limited to only the inside layers of the bowel, about 80--90% will survive 5 or more year - If cancer has spread to nearby lymph nodes, the chances of surviving 5 years are about 50-60% - If the cancer already has spread to the liver and other organ, the chance of living 5 years is less than 10%.
Conclusion Colon cancer is one of the leading causes of cancer and death from carcinoma in the United States. Despite the increased awareness of this cancer for the past 40 years, the mortality has not improved significantly. There are no real magical cures in terms of drugs in the near future. Prevention of the cancer is one of the ways which has been recommended to decrease the mortality from this cancer. Screening of individuals above the age of 50 has been recommended. However, a significant number of the American population does not have the medical coverage and the costs for annual screening are prohibitive. Until some type of universal Federal program which pays for the screening is available, the mortality of colon cancer is unlikely to change.