Prognostic stratification of oestrogen receptor-positive HER2-negative lymph node-negative class of breast cancer.

Multigene assay is currently recommended for prognostic stratification of the clinically indeterminate group of breast cancer (BC) patients defined as lymph node (LN)-negative, oestrogen receptor (ER)-positive HER2-negative (LN-/ER+/HER2-) to determine the use of chemotherapy. However this cohort, comprising approximately 40% of BC, is not a homogeneous group and shows variable outcome. This study aims to determine the prognostic value of routinely assessed variables, singly and in combination, in the LN-/ER+/HER2- BC. Methods 830 LN-/ER+/HER2- chemotherapy naive BCs were investigated. The prognostic value of histologic grade, tumour size, lymphovascular invasion (LVI), progesterone receptor (PgR) and Ki67LI was assessed. In this series, only 25% of patients received hormone therapy. Median follow-up was 172 months. Results In the whole cohort, tumour grade, size, LVI, PgR and Ki67LI were highly correlated with outcome in a time-dependent manner. The outcome of this group varied widely from 97% (20% of cases) to 50% survival rate after 10-year follow-up using combination of these markers. A prognostic index (Nottingham Px) incorporating grade, size, PgR and Ki67LI was developed. The index can robustly stratify the whole cohort as well as the higher risk subgroup (NPI score >3.4) into distinct prognostic classes. Conclusion Current routinely assessed variables can provide additional prognostic information in LN-/ER+/HER2- BC. The proposed (Nottingham Px) index can stratify BC clinically indeterminate group of patients into excellent and poor prognostic subgroups and can reliably be used to identify patients for systemic chemotherapy or further multigene prognostic testing. Performance of prognostic variables in these tumours is time-dependent and should be considered in future studies. This article is protected by copyright. All rights reserved.