Pharmacogenetics and pharmacogenomics (PGx) are rapidly growing fields that aim to elucidate the genetic basis for the interindividual differences in drug response. PGx approaches have been applied to many anticancer drugs in an effort to identify relevant inherited or acquired genetic variations that may predict patient response to chemotherapy and targeted therapies. In this article, we discuss the advances in the field of cancer pharmacogenetics and pharmacogenomics, driven by the recent technological advances and new revolutionary massive sequencing technologies and their application to elucidate the genetic bases for interindividual drug response and the development of biomarkers able to personalize drug treatments. Specifically, we present recent progress in breast cancer molecular classifiers, cell-free circulating DNA as a prognostic and predictive biomarker in cancer, patient-derived tumor xenograft models, chronic lymphocytic leukemia genomic landscape, and current pharmacogenetic advances in colorectal cancer. This review is based on the lectures presented by the speakers of the symposium "Pharmacogenetics and Pharmacogenomics as Tools in Cancer Therapy" from the VII Conference of the Spanish Pharmacogenetics and Pharmacogenomics Society (SEFF), held in Madrid (Spain) on April 21, 2015.