Matthew P. Goetz, MD

In the post–Human Genome Project era, “personalized medicine” has become a buzzword. Health-care professionals increasingly have access to gene sequence data, with the promise that this information will improve the health of the individual. In the area of breast oncology, the study of genetic markers associated with clinical outcome has been a relative success story.

Breast cancer is the most common female malignancy in the Western world. Two-thirds of all breast cancers are estrogen receptor (ER)-positive, a phenotypic characteristic that is prognostic of disease-free survival and predictive of response to endocrine therapy.