Detection device (1) for detecting volatile organic compounds in faecal gases, which device is suitable for a preliminary screening of cancer/adenoma of the colon-rectum and comprises: • - a container (6) of a feces sample; • - a plurality of sensors (3), each configured for detecting respective volatile organic compounds of faecal gases; • - a pump (40) to supply a flow of air on the feces sample and to said sensors (3), said pump being associated to a pneumatic circuit (41) and to flow regulators (45, 46); and • - a processing unit (5), in communication with said sensors, configured to provide an output datum on the presence of cancer/ adenoma of the colon-rectum.