Known to hamper diagnosis, it helps detect colon cancer
COLORECTAL cancer is a leading cause of mortality in both developed and developing countries. Screening methods for colon cancer depend on detecting the precancerous changes. Generally, colonoscopy is carried out but the test is expensive (Rs 25,000-Rs 30,000) and the procedure highly invasive. An alternative is Fecal Occult Blood Test (FOBT) which detects subtle blood loss in the gastrointestinal tract. The test does not directly detect colon cancer and shows positive in case of any kind of gastrointestinal bleeding. This results in many false positives.
“A positive test for gastrointestinal bleeding can also result from jaundice, sickle cell anaemia or a bleeding peptic ulcer,” said Rajni Mutneja, senior oncologist, Rajiv Gandhi Cancer Institute and Research Center, New Delhi. Of all the patients testing positive with FOBT, only 2-10 per cent are detected with cancer later, she added.
Researchers at the German Cancer Research Centre in Heidelberg, Germany, have found that giving low-doses of aspirin prior to FOBT helps in better detection of colorectal cancer. The risk of colon cancer rises with age, with more than 90 per cent of cases occurring in people over the age of 50.
It was believed that aspirin leads to increased bleeding and false results. People who underwent FOBT were advised to go off the drug. Aspirin’s blood-thinning properties prompt doctors to prescribe its low-doses to those at risk of cardiovascular diseases.
Hermann Brenner and his colleagues assessed the association between low-doses of aspirin and performance of FOBTs in a sample of 1,979 patients with an average age of 62 years. The study was conducted over a period of four years (2005-2009). They were divided according to aspirin usage (regular users and non-users).
The study found the sensitivity of FOBTs was twice for low-dose aspirin users as compared to that of non-users in both the tests. The results were more accurate as well. “Our study suggests that use of low-dose aspirin does not hamper testing of the cancer, on the contrary, it enhances test performance,” said Brenner.
The study was published in the December 8 issue of the Journal of American Medical Association.
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