Dogs for this study would be trained by the "Dogs for People" association. In the initial stage, 40 mixed breed dogs and 3-4 Springer spaniels would be exposed to sweat sample collected from cancer patients in order to get them acquainted with the scent. Then, it would be demanded of them to locate boxes containing T-shirt sample taken from cancer patients, from decoy boxes holding naïve T-shirts. Every sequence will include 4 boxes with a different ratio between the specimens(each time a different number of boxes will contain samples taken from cancer patients, 0,1,2,3 or 4 when the rest of the boxes would contain naïve T-shirts). The dogs would mark the specimen by sitting next to each relevant box (they will ignore the decoy boxes after sniffing them and identifying them as irrelevant).