Noninvasive diagnostic tools in colorectal cancer mass screening

Colorectal cancer is one of the most common malignancies in developed countries. Although guaiac-based fecal occult blood tests have proven their efficacy for screening, they have major drawbacks. Immunochemical fecal occult blood tests are theoretically superior as they can detect very small amounts of hemoglobin, and they are specific to human hemoglobin. Recently many different immunochemical tests have been marketed, with variations in hemoglobin detection limit, mechanism of action, sample collection method, and test development. Molecular tests represent an alternative to fecal blood tests, which have been designed to detect certain fecal DNA mutations, or aberrant gene methylation (either hyper-or hypomethylation). In this review, we discuss a selection of the most significant studies published in the last 3 years regarding noninvasive tools for colorectal cancer screening.