Dr. Ellis on Ki67 as Treatment Monitoring Biomarkers

Matthew J. Ellis, MD, PhD, director, Section of Breast Oncology, Division of Oncology, Department of Medicine, Washington University, St Louis, MO, explains the use and efficacy of Ki67 as a treatment monitoring biomarker in hormone receptor (HR) positive breast cancer.

Ellis explains that this is not a new concept, therapy-monitoring markers are used throughout medicine and classic examples include monitoring glucose levels, blood pressure and other items. Treatment monitoring biomarkers are often the most useful markers in medicine.

Researchers have started looking at the Ki67 marker to measure cell-proliferation before and after endocrine therapy in the neo-adjuvant setting for HR-positive breast cancer. Measuring the amount of cells growing in the tumor during the endocrine setting can be a better predictive marker of how a patient will do in the long-term compared to measuring at the beginning of the therapy alone.

As an example he uses patients with high blood pressure receiving diuretics. In some patients the blood pressure will fall with a lower likelihood of stroke, in others it will not decrease and another treatment is necessary. This type of monitoring can help decide how to advance treatment.

Tumors that have a positive Ki67 index after receiving endocrine therapy often do much worse and will require more attention or a new treatment.