Cancer and Coronary Heart Disease (CHD) are the major health problems all over the world. The main obstacle facing cancer and CHD prevention is a lack of precise approach for early detection and prevention of these diseases. Most previous works on these diseases dealt with only infected patients. New technique under accurate statistical experimental design must be developed in order to early detect and diagnose of these diseases. Therefore, genotype-environment interaction, which indicates the different responsiveness of various genotypes to different environment (drugs) can play an important issues to be cosidered by pathologists, pharmacists and molecular geneticists in ivestigating, detection, diagnosing and treating diseases.