Releasing individuals from susceptibility to and anxiety about the development of cancer is an eventual goal of cancer research. This owes much to rapid progress in molecular oncology that is supported by advances in technology. Cancers of the colon and rectum, pancreas and lung that share certain clinical and molecular oncological characteristics represent timely and important target of this field. Of the genes altered in these types of cancers, the best documented is K-ras. Currently highlighted along with this oncogene is beta-catenin, which has roles in both cell adhesion and transformation. Molecular diagnosis and susceptibility assessment targeting of such oncogenes will be promising for improvement in treatment and prevention of cancer, thereby contributing to human healthcare. Here we review recent knowledge on molecular diagnosis of sporadic cancers, with focus on K-ras and beta-catenin oncogenes.