Genomics and Pharmacogenomics of Breast Cancer: Current Knowledge and Trends

The impact of genomics and pharmacogenomics in the current arena of clinical oncology is well-established.In breast cancer, mutations in the BRCA1 and BRCA2 genes have been well-characterized to carry a high riskof the disease during a woman’s lifespan. However, these high risk genes contribute to only a small proportionof the familial cases of breast cancer. Hence, further efforts aimed to study the contribution of genetic mutationsin other genes, including the estrogen receptor gene, TP53, CYP19, and mismatch repair genes to furtherinvestigate the genetic component of breast cancer. Multiple pharmacogenomic studies have previously linkedgenetic variants in known pathways with treatment response in cancer patients. Currently, polymorphisms indrug metabolizing enzymes, efflux transporters, as well as, drug targets have shown correlations to variations inresponse and toxicity to commonly prescribed chemotherapeutic treatments of breast cancer. CYP2D6 variantshave been correlated with tamoxifen response and interindividual variability seen. An emerging application ofcancer genetics and pharmacogenetics involves the use of inherited or acquired genetic abnormalities to predicttreatment toxicity or outcomes. Recently, methods that involve the scanning of entire genomes for common variantshave begun to influence studies of cancer causation. Currently, treatment individualization for breast cancer cantake place on the basis of few molecular targets including the estrogen receptor and the overexpression of theHER2 receptor. Overall, the current review summarizes the recent findings in the genetic and pharmacogeneticresearch of breast cancer and the advances made in personalization of treatment.