Real-World Assessment of Locoregional Management of the Axilla in Node-Positive Breast Cancer After Neoadjuvant Chemotherapy

BackgroundThere is limited level I evidence guiding axillary management in patients with node-positive breast cancer downstaged post-neoadjuvant chemotherapy (NAC) to clinically node-negative. We aimed to describe practice patterns among cN+ patients after NAC and examine predictors of subsequent completion axillary lymph node dissection (cALND) and recurrence among patients who initially underwent sentinel lymph node biopsy (SLNB).Patients and MethodsThis was a retrospective, population-based cohort of patients with cN+ breast cancer who underwent NAC then surgery in Alberta from January 2016 to September 2021. Practice patterns were described. Chart review was performed for patients receiving definitive SLNB at the index surgery; the outcomes were rates of subsequent cALND and recurrence.ResultsThe total cohort comprised 850 patients. Median age was 52 years, 584 patients (68.7%) had cT1/T2 disease before NAC, and 395 patients (46.5%) were HR+/HER2-. A total of 472 patients (55.5%) underwent SLNB but 108 were converted intraoperatively to ALND. On final pathology, 189/364 (51.9%) had a pathologic complete response, and most (95.1%) had adjuvant RT. Only 39 ypN+ patients (22.2%) had a cALND. After a median of 46.7 months, 52/364 (14.3%) patients recurred; 7/10 patients with regional recurrence did not undergo cALND, but 2 subsequently underwent salvage ALND. On multivariate analysis, very high/low body mass index (BMI), triple-negative disease, cT3/4 disease pre-NAC, and positive SLNB were predictors of recurrence.ConclusionsUptake of cALND for ypN+ patients in a real-world setting with frequent administration of RT was lower than expected. Regional recurrences were rare, suggesting that a nuanced approach to cALND may be feasible.