Personal medicine is based on purposeful treatment that, unlike traditional therapies, considers a person's genetic structure and medical history before establishing a treatment regimen. This science has made possible the improvement of "pharmacogenomic" knowledge, which identifies individuals who respond to a particular treatment based on their genotype information. The findings of the Cancer Genome Atlas Network show that each molecular endorsement of each BCis unique. Also, different responses to a given medication regimen have been reported among a similar group of breast cancer. Thus, personal medicine plays a role in the care of patients with breast cancer, in which a person's characteristics, including genetic characteristics, guide clinical decisions and are effective in choosing the right treatment for the patient at the right time.