Introduction: The MonarchE trial explored the use of abemaciclib, a CDK4/6 inhibitor, as an adjuvant treatment in high-risk early-stage luminal-like breast cancer. The study's inclusion criteria, especially the N2 status, may require revisiting surgical interventions, including invasive axillary lymph node dissection (ALND)-a procedure that current guidelines generally do not recommend.
Methods: We conducted a single-centre, retrospective, observational cohort study on non-metastatic breast cancer patients managed from 2002 to 2011, at the Institut Curie. Data collection involved clinical and histological characteristics plus treatment follow-up.
Results: Out of 8715 treated patients, 721 met the inclusion criteria. Overall, 12% (87) were classified as N2 ( ≥ 4 positive lymph nodes), thus eligible for abemaciclib per "node criterion." Tumour size, positive sentinel lymph nodes, and lobular histology showed a significant correlation with N2 status. Approximately 1000 ALNDs would be required to identify 120 N2 cases and prevent four recurrences.
Conclusion: The MonarchE trial may significantly affect surgical practices due to the need for invasive procedures to identify high-risk patients for adjuvant abemaciclib treatment. The prospect of unnecessary morbidity demands less invasive N2 status determination methods. Surgical decisions must consider patient health and potential treatment benefits.
© 2024. The Author(s), under exclusive licence to Springer Nature Limited.