Examples include the individualized classification of breast cancers through RNA profiling, the use of NGS to identify actionable mutations such as epidermal growth factor receptor and anaplastic lymphoma kinase in lung cancer, and the use of immunohistochemical staining for proteins such as Kirsten rat sarcoma viral oncogene to guide treatment decisions in colorectal cancer. This paper carefully examines how molecular biology is essential to creating new strategies to fight this difficult and widespread illness. This evidence concerns the gene EGFR and breast cancer.