A number of promising approaches against human cancer become available in the post genome era. For cancer prevention, a series of genome-wide association study is being performed and several SNPs that could predict susceptibility of cancer, including breast and gastric cancers, have been identified successfully. For cancer treatment, growing numbers of molecular-targeting drugs are being challenged, in which inhibitors of EGFR tyrosine kinase, including gefitinib, have been established for treatment of a subset of lung adenocarcinoma. Detection of the specific EGFR mutations is shown to predict response of individual tumors to gefitinib. Mamma-Print, a microarray-based analysis of breast cancer, is also successfully used for predicting response of breast cancer to Herceptin. Molecular targeting therapy in combination with such genome-based analyses could provide effective personalized medicine against human cancer.