Therapeutic escalation - De-escalation: Data from 15.508 early breast cancer treated with upfront surgery and sentinel lymph node biopsy (SLNB).

Introduction: The aim of this study was to examine changes in therapeutic practices for early breast cancer T0-2 N0 managed by upfront surgery and SLNB.

Population: Between 1999 and 2012, 15.508 patients were treated. Four periods were determined: 1999-2003, 2004-2006, 2007-2009 and > 2009. Five tumor subtypes were defined according to hormonal receptors (HR) and Her2: Luminal A (HR + Her2- Grade 1-2), Her2 (Her2+ HR-), Triple-negative (HR- Her2-), Luminal B Her2- (HR + Her2- Grade 3), Luminal B Her2+ (HR + HER2+).

Methods: Rates of axillary lymph node dissection (ALND), adjuvant chemotherapy ± trastuzumab, endocrine treatment, mastectomy and post mastectomy radiotherapy (PMRT) were analyzed according to treatment periods with univariate and multivariate analysis. Overall and disease-free survivals were analyzed according to treatment periods adjusted for HR and then for tumor subtypes.

Results: Rates of ALND, adjuvant chemotherapy and endocrine treatment varied significantly according to treatment periods, for HR positive and negative tumors. ALND rate decreased for all tumor subtypes with a decrease of adjuvant chemotherapy rate for Luminal A tumors and an increase for Luminal B Her2+ and Her2-tumors. Endocrine treatment rate decreased for Luminal A and increased for Luminal B Her2+ tumors. In multivariate analysis, these modifications with time remained significant. Mastectomy and PMRT rates increased. In multivariate analysis, overall and disease-free survivals increased during successive periods.

Conclusion: A global therapeutic de-escalation in ALND and adjuvant systemic treatment, combined with an actual escalation in some specific subsets was demonstrated, but without negative impact on survival.