De-escalation of axillary surgery in breast cancer patients treated in the neoadjuvant setting: a Dutch population-based study.

ABSTRACT

PURPOSE: An overall trend is observed towards de-escalation of axillary surgery in patients with breast cancer. The objective of this study was to evaluate this trend in patients treated with neoadjuvant systemic therapy (NST). METHODS: Patients with cT1-4N0-3 breast cancer treated with NST (2006-2016) were selected from the Netherlands Cancer Registry. Patients were classified by clinical node status (cN) and type of axillary surgery. Uni- and multivariable logistic regression analyses were performed to determine the clinicopathological factors associated with performing ALND in cN+ patients. RESULTS: A total of 12,461 patients treated with NST were identified [5830 cN0 patients (46.8%), 6631 cN+ patients (53.2%)]. In cN0 patients, an overall increase in sentinel lymph node biopsy (SLNB) only (not followed by ALND) was seen from 11% in 2006 to 94% in 2016 (p < 0.001). SLNB performed post-NST increased from 33 to 62% (p < 0.001). In cN+ patients, an overall decrease in ALND was seen from 99% in 2006 to 53% in 2016 (p < 0.001). Age (OR 1.01, CI 1.00-1.02), year of diagnosis (OR 0.47, CI 0.44-0.50), HER2-positive disease (OR 0.62, CI 0.52-0.75), clinical tumor stage (T2 vs. T1 OR 1.32, CI 1.06-1.65, T3 vs. T1 OR 2.04, CI 1.58-2.63, T4 vs. T1 OR 6.37, CI 4.26-9.50), and clinical nodal stage (N3 vs. N1 OR 1.65, CI 1.28-2.12) were correlated with performing ALND in cN+ patients. CONCLUSIONS: ALND decreased substantially over the past decade in patients treated with NST. Assessment of long-term prognosis of patients in whom ALND is omitted after NST is urgently needed.