Recent studies have revolutionized our understanding of the genomic underpinnings of cancer development and progression. This knowledge has led to new methods of diagnosing and treating cancer. Emerging clinical applications of cancer genomics include monitoring treatment responses and indicating ways of resistance. With advancement in DNA analysis, the scope of genetic testing has widened in diﬀerent areas, mainly in pharmacogenomics, predictive testing, and prenatal testing. Genetic testing also enhances the early detection of breast cancer.