The increasing use of pre-operative systemic therapy has resulted in more limited information about axillary lymph node status, both from the impact of systemic therapy itself as well as from less extensive axillary surgery. Decisions about the use of adjuvant endocrine therapy have not been majorly affected, but information on the presence and number of involved lymph nodes can have a significant influence on the use of adjuvant chemotherapy and HER-2 targeted therapies. In addition, lymph node information can also impact decisions around radiation therapy, making multidisciplinary discussions highly relevant when planning therapy. Patients with hormone receptor positive breast cancer may be treated with pre-operative endocrine therapy. This strategy was often used in early stage breast cancer during the COVID pandemic due to delays in surgery. Although an effective approach, pre-operative endocrine therapy may impact nodal status at surgery, information which is important when deciding on the use of OncotypeDX testing in premenopausal women. Similarly, in postmenopausal women, the presence and number of lymph nodes involved is a critical factor in determining the appropriateness of OncotypeDx testing. This nodal information may be lost in the setting of pre-operative therapy and would alter decisions regarding adjuvant chemotherapy. For patients with HER2 positive breast cancer, the presence of nodal disease remains critical for adjuvant decision making. In the situation of small (up to 3 cm) node negative cancers, up front surgery is preferred, because pathologic confirmation of the tumor size and node negative status may make patients eligible for a de-escalated approach of adjuvant paclitaxel and trastuzumab. Patients with more advanced HER2 positive disease are good candidates for preoperative chemotherapy and HER2 targeted therapy. If they have residual disease at surgery, they can be offered trastuzumab emtansine, which was shown in the KATHERINE trial to improve outcomes. In both situations, accurate information about the presence of disease in the axillary lymph nodes determines the most effective treatment approach. Finally, accurate information about nodal status is also relevant to decisions in patients with triple negative breast cancer. Patients who are treated with pre-operative chemotherapy and have residual disease in either the breast or axillary lymph nodes may be offered adjuvant capecitabine, based on the CREATE-X study, which indicated improved survival outcomes in those patients with residual disease who received adjuvant capecitabine. As in HER2 positive breast cancer, the presence of residual disease (including in the lymph nodes) after preoperative therapy will influence the adjuvant therapy recommendation. Thus, when considering de-escalation approaches in axillary management, the impact on systemic therapy decision making must be carefully considered, as these additional adjuvant therapies may improve survival for patients. Conflict of Interest: No significant relationships.
Adjuvant decision making in the era of limited nodal information