Death for tumors is a worldwide health problem, with colorectal cancer (CRC) in particular showing to be one of the malignant tumors with the highest incidence for both genders, and with high mortality rate if not treated in time. To gain advantage on the neoplasia, and being able to identify and remove CRC in his benignant stage, pre-screening protocols like fecal occult blood test (FOBT) have been developed, and high interest from the scientific community have been shown on electronic noses, able to detect particular tumor markers secreted from cancer cells, different from blood (which may not show up at all in some cases). The goal of this book is to show the results obtained, thanks to an ongoing and recognized research from the Laboratory of Sensors of the University of Ferrara, with a different kind of technological approach, starting from the laboratory setup gases tests to the patented threshold system, based on nanostructured chemoresistive sensors, to detect the presence of both benignant polyps and CCR from the samples of feces obtained from people willingly to monitor themselves with this brand new pre-screening test.