Dr. Ellis Describes Breast Cancer Heterogeneity

Matthew J. Ellis, MD, PhD, professor of medicine, director, Breast Cancer Program, Siteman Cancer Center, describes how cryptic mutations, previously undetected base changes in genetics, contribute to tumor heterogeneity in women with breast cancer.

Ellis explains that a whole genome sequence in hormone receptor (HR)-positive patients that are undergoing endocrine therapy, before treatment and 4-5 months into treatment, provides an accurate picture of how the tumor changes.

At 4-5 months immunohistochemistry will still show that the patient is still HR-positive but a closer look at the cryptic mutations will reveal multiple changes. Rare mutations in the pretreatment phase can become more common while the prevalent mutations drop out. This type of heterogeneity reveals the hidden complexity of breast cancer.

In order to find the best treatment for patients, researchers and physicians need to fully embrace heterogeneity. The concept of a constantly adjusting and changing tumor alters treatments.