Dr. Ellis on Heterogeneity Impacting Biomarker Efficacy

Matthew J. Ellis, MD, PhD, professor of medicine, director, Breast Cancer Program, Siteman Cancer Center, discusses the impact of heterogeneity on the efficacy of biomarkers for patients with breast cancer.

Ellis believes it is very important for the modern pathologist to look for and report heterogeneity when examining standard biomarkers, such as the immunohistochemistry, straight histology, and HER2 testing.

In breast cancer it is common to see high-grade areas within a predominantly low-grade tumor. Despite these high-grade areas, the overall grade is generally reported as an average. This problem occurs for multiple types of heterogeneity; as an example, Ellis asks the question of how tumors with an area of high proliferation or that are 10% ER-positive should be reported and treated.

Difficulties that arise due to heterogeneity make predicting outcomes more difficult using biomarkers. Ellis states, while the markers do well, they can never do great because of this phenomenon.