Genomics in ‘Personalised’ Management of Breast Carcinoma

Breast cancer is a disease caused by a host of factors which also include accumulation of genetic aberrations over a period of time. Most breast cancers occur at random; however, germline mutations leading to hereditary cancer are seen in around 10–15% cases. Molecular testing for genetic and genomic variation for both hereditary and sporadic breast cancer is now essential for diagnosis, prognostication and therapeutics. This will be discussed in detail in this chapter. The role of breast carcinoma-vulnerable genes in familial carcinoma and evolving role of PARP inhibitors for BRCA1 and 2 mutant cancers will also be discussed. Breast carcinoma is subdivided in molecular subtypes depending on genetic array testing and receptor status along with proliferation markers like Ki-67. These subtypes are reproducible, and their effect on prognosis is verified in multiple situations. The molecular subtypes have been discussed in detail in this chapter. Apart from surgery, radiation and chemotherapy, current management of early and advanced breast carcinoma is concerned with targeting oestrogen and HER2 receptors and other molecular targets such as mTOR, PI3K and CDK4/6. This chapter also presents a comprehensive overview on the role of ‘personalised’ receptor-based targeted treatment for breast carcinoma.