HEIDELBERG, Germany—Use of low-dose aspirin prior to a newer type of fecal occult blood test is associated with a higher sensitivity for detecting advanced colorectal tumors, compared to no aspirin use, according to a study in the December 8 issue of JAMA.
"Screening for colorectal cancer (CRC) and its precursors by fecal occult blood tests (FOBTs), which has been shown to reduce CRC incidence and mortality in randomized trials, is widely recommended and applied in an increasing number of countries. Screening is mostly done in age groups in which use of low-dose aspirin for primary or secondary prevention of cardiovascular disease is increasingly common. Use of low-dose aspirin increases the likelihood of gastrointestinal bleeding, especially upper gastrointestinal bleeding.
Because of the increased risk of bleeding from sources other than colorectal neoplasms [tumors], concerns have been raised regarding possible adverse effects on specificity of FOBT-based screening for CRC," according to background information in the article. Potential false-positive test results due to increased risk of upper gastrointestinal bleeding are expected to be of less concern for increasingly available immunochemical FOBTs (iFOBTs; a type of test to check for blood in the stool), but evidence is sparse about the performance of iFOBTs for patients who use low-dose aspirin.
Hermann Brenner, MD, MPH, of the German Cancer Research Center, Heidelberg, Germany, and colleagues assessed the association of use of low-dose aspirin with performance of 2 iFOBTs in a large sample of women and men who underwent CRC screening. The study, conducted from 2005 through 2009, included 1,979 patients (average age, 62.1 years): 233 regular users of low-dose aspirin (167 men, 67 women) and 1,746 who never used low-dose aspirin (809 men, 937 women). The researchers analyzed measures of sensitivity and specificity in detecting advanced colorectal neoplasms (colorectal cancer or advanced adenoma [a tumor that is not cancer]) with 2 quantitative iFOBTs (hemoglobin test and hemoglobin-haptoglobin [a protein] test).