DR. J.P. AHLUWALIA: Colon cancer is a common disease and is the second leading cause of cancer deaths in the United States. Approximately one in three people who develop colon cancer die of this disease. An estimated 150,000 patients are diagnosed with colon cancer each year in the U.S. If diagnosed at an early stage, colon cancer can be treated easily and often can be cured.
Age is a major risk factor for the development of colon cancer. It is rare in patients younger than 40. Ninety percent of the cases occur after the age of 50. However, the incidence is much higher in patients with specific inherited conditions that put them at increased risk of developing colon cancer. In some inherited conditions, such as familial adenomatous polyposis, numerous precancerous growths called colon polyps can appear even during childhood. Colon cancer develops in 90 percent of the untreated individuals by age 45.
Patients should see their doctors with concerns about blood in their stools, black stools, abdominal pain, iron deficiency anemia or a change in their usual bowel habits. Weakness, loss of appetite and weight loss also have been described in patients who are diagnosed with colon cancer. Symptoms that should cause immediate alarm are dark red rectal bleeding and abdominal mass as they are highly indicative of colon cancer.
Colon cancer may be suspected in patients with one or more of these signs and symptoms. Patients who have these symptoms at the time of diagnosis of colon cancer usually have a somewhat worse prognosis. However, many patients have no symptoms so their disease is found during routine screening.
A majority of colon cancers arise from the lining of the colon. Many different tests have been studied over the years for screening of patients who have no symptoms or for further evaluating patients with signs and symptoms. A colonoscopy utilizes a direct view of the entire colon performed by specially trained physicians to detect precancerous growths, including small polyps. So gastrointestinal societies, including the American College of Gastroenterology (ACG) and the American Society for Gastrointestinal Endoscopy (ASGE), believe this to be the single best test.
While flexible sigmoidoscopy, barium enema and CT colonography, also known as virtual colonoscopy, have been described as alternatives, a follow-up colonoscopy will be required for those patients where anything suspicious is discovered using one of these tests. Colonoscopy also offers the advantage of both finding precancerous growths and removing them in a single examination.
It is estimated that about 50 percent of Americans who should be getting screened for colon cancer, a largely preventable disease, are not undergoing screening. The data also shows that screenings that come from colon cancer awareness efforts save lives. Screenings can lead to better outcome because of earlier detection.
Dr. J. P. Ahluwalia is an associate professor of internal medicine at Southern Illinois University School of Medicine.
Useful links to gastrointestinal societies -
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