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 risk of the disease during a woman's lifespan. However, these high risk genes contribute to only a small proportion of the familial cases of breast cancer. Hence, further efforts aimed to study the contribution of genetic mutations in other genes, including the estrogen receptor gene, TP53, CYP19, and mismatch repair genes to further investigate the genetic component of breast cancer. Multiple pharmacogenomic studies have previously linked genetic variants in known pathways with treatment response in cancer patients. Currently, polymorphisms in drug metabolizing enzymes, efflux transporters, as well as, drug targets have shown correlations to variations in response and toxicity to commonly prescribed chemotherapeutic treatments of breast cancer. CYP2D6 variants have been correlated with tamoxifen response and interindividual variability seen. An emerging application of cancer genetics and pharmacogenetics involves the use of inherited or acquired genetic abnormalities to predict treatment toxicity or outcomes. Recently, methods that involve the scanning of entire genomes for common variants have begun to influence studies of cancer causation. Currently, treatment individualization for breast cancer can take place on the basis of few molecular targets including the estrogen receptor and the overexpression of the HER2 receptor. Overall, the current review summarizes the recent findings in the genetic and pharmacogenetic research of breast cancer and the advances made in personalization of treatment.