How can we optimize the surgical management of the axilla in breast cancer since the MonarchE trial ?

Abstract Purpose Results of MonarchE trial have changed adjuvant therapy for estrogen-receptor-positive(ER+), HER-2-negative breast cancer. Given the importance of the extent of nodal disease in this study, surgical management of the axilla has resurfaced as a question asked at multidisciplinary boards. Methods Using data from a cohort of Werkoff (JCO, 2009) in which patients underwent both sentinel lymph nodebiopsy(SLNB) and axillary node dissection(ALND), we assessed the proportion of patients in whom the absence of ALND would have led to a lack of awareness of "high-risk" status. We evaluated the contribution of the Katz nomogram (that predict pN2/N3 stage) to guide possible indications for complementary ALND. Results Among the 536 patients, 88 were excluded (ER- and/or isolated cells in SLN). Of patients with 1 or 2 SLN+(n = 352), only 7.9% were pN2/N3. When the ratio (number of SLN+/total number of SLN sampled) was less than 1, only 3.9% were pN2/N3. Patients with 1 or 2 SLN + met the ACOSOG Z0011 criteria so none would benefit from an ALND, but 7.9% of patients at high risk will not receive Abemaciclib. If we use the Katz nomogram (threshold ≤ 5%), this rate decrease at 3.3% but 116 patients will have an ALND with no benefit. With a threshold ≤ 20%, 5% patients at high risk will not receive Abemaciclib but 21 patients will have an ALND with no benefit. Conclusion The indications for adjuvant Abemaciclib should not lead to surgical escalation in the management of the axilla.