There is also increase in the importance of the role of predictive tumourmarkers in managing a patient’s response to treatment leading tochoosing the right drug for right patient such as Her-2 geneoverexpression in gastric cancers and mutational status of Kras gene incancer colon and CD117 (KIT) overexpression in gastrointestinal stromaltumors. In gastric cancers, overexpression of the HER2 protein seems topossess the best predictive value for treatment with trastuzumab.