Breast
Olga Kantor, MD MS
Breast Surgeon
Brigham and Women's Hospital
Boston, Massachusetts, United States
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
The RxPONDER trial randomized HR+HER2- breast cancer patients (pts) with 1-3 pos nodes and Recurrence Score (RS) < 26 to endocrine therapy (ET) vs chemoendocrine therapy (CET) with no survival difference in postmenopausal women. In current practice many pts have sentinel lymph node (SLN) biopsy (SLNB) alone, raising concerns about applying these data in +SLN pts who may have additional non-SLN metastases.
Methods:
A prospective institutional database (DF/BWCC) was used to examine nodal disease burden and CET use in cT1-3N0 HR+HER2- pts age 50-75 with 1-3 +SLN and RS < 26 treated with upfront surgery and CET/ET from 2015-2019. We paired this with similar pts captured in the NCDB from 2012-2017. Treatment patterns and outcomes were assessed based on number of +SLN and use of CET.
Results:
203 and 13,499 HR+HER2- eligible pts with RS < 26 were identified in the DF/BWCC and NCDB databases. CET rates were 5.4%, 13.8%, and 0% in pts with 1,2, or 3 +SLN in the DF/BWCC (p=0.26) and 17.8%, 29.7%, and 36.4% in the NCDB (p< 0.01). 27 (13.3%) DF/BWCC and 4,368 (32.4%) NCDB pts had ALND. Of these, only 11.1% and 4.9% had >3 total pos nodes, respectively (Table).
Multivariable analysis found higher RS to be a significant predictor of CET in both cohorts (OR 15.6 in DF/BWCC; OR 2.16 in NCDB for RS >17). Additional predictors of CET in the NCDB included T stage (OR 2.41 for T3), grade 3 disease (OR 2.16), and number of pos nodes (OR 2.02, 2.63, and 9.93 for 2, 3, or >3 pos nodes). At a median of 44.1 months there were no differences in adjusted 5-yr OS between pts treated with CET or ET regardless of number of pos nodes (97.8% CET vs 97.0% ET for 1, 97.9% vs 97.5% for 2, 99.5% vs 99.3% for 3, all p >0.05) in the NCDB cohort.
Conclusions: cT1-3N0 HR+HER2- breast cancer pts are unlikely to have >3 total pos nodes. Low rates of ALND suggest that prior to RxPONDER clinicians were comfortable staging the axilla with SLNB alone, and outcomes were not impacted by number of +SLN. As such, CET decisions should continue to be based on SLN positivity and ALND should not be performed for this purpose.