Patients with positive axillary lymph nodes: how to use genomic assays

The treatment of breast cancer is continually evolving. Standard treatment for early stage, node positive breast cancer has included adjuvant chemotherapy. As we learn more about differences in a tumor's genetic makeup that result in different patterns of recurrence and survival, we are starting to include gene expression in addition to the routine clinical and pathological factors when we make treatment recommendations. For lymph node negative, early stage breast cancer, there are two genomic assays in routine use to predict prognosis and benefit from adjuvant chemotherapy. There is emerging data to support that the same tests may also predict prognosis and chemotherapy benefit, or lack thereof, in lymph node positive tumors. Currently there are no standard of care and this is an area in which more research is being done. Given that the biology of breast tumors is independent of nodal status, there are certainly cases of node positive early stage breast cancer where clinicians can feel comfortable making treatment decisions based on genomic assays. These include women with micrometastases in the lymph nodes or those with one to three positive lymph nodes. Currently, the genomic assays are limited to use in tumors that are estrogen receptor positive. It is still clearly the standard of care to administer chemotherapy to estrogen receptor negative, lymph node positive tumors.