Genomic and Proteomic Applications to Breast Cancer

I recently completed my two-year term as Program Chairman of the National Consortium of Breast Centers and have returned from the 19th Annual Interdisciplinary Breast Care Conference, held in Las Vegas, NV. It was an unbelievable program and really stressed how important it is that any of us that take care of breast cancer be aware and up to date on the developments across the specialties also involved. I heard talks on breast MRI, new radiology technologies like breast-specific gamma imaging, the future of breast surgery, genetic risk and breast cancer prevention. One of the most fascinating talks I heard though was delivered by Col. Craig Shriver of Walter Reed Army Medical Center. He heads the Clinical Breast Care Project and discussed the genomic and proteomic applications to breast cancer evolution, treatment, and classification.

As part of his talk he focused on the nodal spread of breast cancer as it leaves the breast to involve the axillary sentinel node and then other nodes. The clinical assumption is that the primary cancer in the breast and the axillary metastasis is essentially the same tumor; it's why we do not order tests for estrogen/progesterone receptors and for HER-2/neu status on specimens obtained from these sites. Routinely, only the breast tumor is tested, and this information is what's used to help formulate a treatment plan.

Dr. Shriver's group aims to describe the origin of breast cancer metastases to the axillary sentinel node and specifically, how and when do cancer cells acquire metastatic potential (see Ellsworth RE, Hooke JA, Love B, Ellsworth DL, Shriver CD. Molecular Changes in Primary Breast Tumors and the Nottingham Histologic Score. Pathol Oncol Res. 2009 Feb 5). Using modern technology, they evaluated the molecular similarities and differences between nodes with cancer in them and the primary breast tumor. Their group found that metastases in the sentinel node look different genetically compared to the primary breast tumor and descend from different areas of the primary breast tumor. Extensive differences in gene expression was seen even within the primary breast tumor, a term called molecular heterogeneity.

The clinical implications of this work are significant. This would help to explain why some disease responds and others do not, particularly relevant as we are giving more chemotherapy up front for women facing mastectomy as their only surgical option for a breast cancer diagnosis. It also implies that testing on both breast and any positive nodes from the axilla should take place more often than not. The challenges on designing a treatment program for the individual could get much more complicated, but in the end, it may serve the patient better than what we are doing now.

For more information on Dr. Shriver's work and my group, the National Consortium of Breast Centers, go to www.breastcare.org.