The science of one’s genetic background and its impact on disease susceptibility and drug response has well established its place in clinics. As many drugs that are currently available in the market are “one size fits all,” but they don’t respond the same way for everyone. These inter-individual differences of drug response can be due to different age, drug-drug interaction, gender, inherited variations in drug disposition or through gene and drug target gene. The impact of Genetic study is mostly observed in the current arena of clinical oncology compared to any other chronic diseases due to several reasons: Toxicity, Critical time & narrow therapeutic index. “Pharmacogenomics” is the whole genome application of Pharmacogenetics, where genomic information is used to study the single gene interactions with drugs by studying the patient’s genetic profile. Their biomarkers hold great promise for the individualization in cancer therapy by selecting the most appropriate medication thereby, applying the optimal dose for each individual patient according to precise markers assisted in screening tests by reducing the toxicity of chemotherapy. Two major aspects considered by researchers while studying the response of a drug in an individual are: how much of a drug is needed to reach its target in the body, and how well the target cells or genes respond to the drug. Overall, the current review summarizes the role of Pharmacogenomics in cancers mainly focusing on Colorectal, Osteosarcoma & Breast Cancer and the advances made in their treatment.