Prognostic effect of nodal status before and after neoadjuvant chemotherapy in breast cancer: a Dutch population-based study

Abstract

Abstract Purpose In breast cancer, neoadjuvant chemotherapy (NAC) can downstage the nodal status, and can even result in a pathological complete response, which is associated with improved prognosis. This study aimed to determine the prognostic effect of nodal status before and after NAC. Methods Women with breast cancer treated with NAC were selected from the Netherlands Cancer Registry if diagnosed between 2005–2019, and classified based on nodal status before NAC: node-negative (cN0), or node-positive based on fine needle aspiration cytology or core needle biopsy (cN+). Subgroups were based on nodal status after NAC: absence (ypN0) or presence (ypN+) of nodal disease. Five-year overall survival (OS) was assessed with Kaplan-Meier survival analyses, also per breast cancer molecular subtype. To adjust for potential confounders, multivariable analyses were performed. Results A total of 6,580 patients were included in the cN0 group, and 11,878 in the cN + group. The 5-year OS of the cN0ypN0-subgroup was statistically significant better than that of the cN + ypN0-subgroup (94.4% versus 90.1%, p < 0.0001). In cN0 as well as cN + disease, ypN + had a statistically significant worse 5-year OS compared to ypN0. For hormone receptor (HR) + human epidermal growth factor receptor 2 (HER2)-, HR + HER2+, HR-HER2+, and triple negative disease, respectively, 5-year OS in the cN0ypN+-subgroup was 89.7%, 90.4%, 73.7%, and 53.6%, and in the cN + ypN+-subgroup 84.7%, 83.2%, 61.4%, and 48.8%. In multivariable analyses, cN + and ypN + disease were both associated with worse OS. Conclusion This study suggests that both cN-status and ypN-status, and molecular subtype should be considered to further improve prognostication.