Axillary Management and Outcomes After Neoadjuvant Endocrine Therapy in the Randomized PELOPS Trial

Data to inform surgical management of the axilla after neoadjuvant endocrine therapy (NET) are limited. Here we report nodal status, surgical procedure, and outcomes among patients enrolled between 2016 and 2020 in the Palbociclib and Endocrine therapy for LObular breast cancer Preoperative Study (NCT02764541).

Women with hormone receptor-positive, HER2-negative tumors > 1.5 cm, any cN, were randomized 2:1 to NET ± palbociclib for 24 weeks. Axillary surgery (sentinel lymph node biopsy [SLNB] ± axillary dissection [ALND]) and nodal evaluation (H&E ± IHC) were not specified in the protocol. Pathologic node-positive (ypN+) rates, local-regional recurrence-free interval (LRRFI), and breast cancer-specific survival (BCSS), compared by univariate Cox proportional hazards, were prespecified exploratory endpoints.

A total of 188 patients were analyzed (128 treated with NET + palbociclib, 60 NET), median age 56.5 years (interquartile range [IQR] 50-66). 82 (43.6%) had lobular histology, 99 (52.7%) were cN0, 84 (44.7%) cN+, and 5 (2.6%) cN unknown. Of cN+ patients with known ypN, nodal pathologic complete response rates were 10.9% (6/55) after NET + palbociclib and 13.6% (3/22) after NET. Among 108 ypN+ patients, 26 (24.1%) underwent SLNB, 82 (75.9%) ALND, and 99 (91.7%) radiation. At 4.65 years (IQR 3.66-5.56) median follow-up, 3-year LRRFI for ypN+ patients treated with SLNB only was 96% (88.6%, 100%) and ALND was 97.4% (93.9%, 100.0%), p = 0.6; 3-year BCSS for SLNB was 96.0% (88.6%, 100.0%) and ALND was 100.0% (100%, 100%), p = 0.9.

The addition of palbociclib to NET did not impact pathologic nodal outcomes. Among those with ypN+ disease, neither LRRFI nor BCSS appears to be impacted by performance of ALND.

clinicaltrials.gov, NCT02764541.