Abstract 173P
Background
In luminal-like early breast cancer (BC), the lack of Progesterone Receptor (PR) expression generally correlates with more aggressive behavior but the clinical validity of low PR values remains a debated issue. The aim of our study is to explore the association between clinicopathological features and prognosis in a cohort of Estrogen Receptor positive (ER+) and Human Epidermal Growth Factor Receptor negative (HER2-) BC patients with different PR expression levels.
Methods
This retrospective analysis included 687 early ER+, HER2- early BC patients treated at our Institutions from January 2000 to December 2017. The clinicopathological parameters and the survival outcomes (Disease Free Survival, DFS and Breast Cancer Specific Survival, BCSS) were assessed between 4 subtypes established on the basis of Ki67 and PR values (Subtype 1: PR≥20%/Ki67<20%; Subtype 2: PR≥20%/Ki67≥20%; Subtype 3: PR<20%/Ki67≥20%; Subtype 4: PR<20%/Ki67<20%) to investigate the prognostic impact of different PR levels. Univariate and multivariate Cox proportional hazard regressions were applied to correlate the clinicopathological variables with DFS and BCSS in overall population.
Results
At a median follow up of 60 months, recurrence occurred in 96 patients and 61 patients died. The comparison of survival curves revealed a significant difference in DFS and BCSS rates among the 4 subtypes (p=0.028 and p= 0.008, respectively). On univariate analysis, high Ki67(≥ 20%), lymph node metastases, larger and poorly differentiated tumors were associated to a higher risk of recurrence and death. Multivariate regression model for DFS and BCSS confirmed Ki67 value as indipendent markers of poor prognosis (p=0.042 and p=0.009 for DFS and BCSS, respectively) while patients with high PR expression (≥20%) reported lower risk of cancer-related death compared to those with weak PR levels (p=0.009).
Conclusions
In our cohort, a statistically significant differences in terms of survival rates were observed among the 4 subtypes of patients. Moreover, these results confirmed PR and Ki67 status as effective prognostic predictors, corroborating their crucial role in the decision-making process of patients with ER+, HER2- early BC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
University of Campania Luigi Vanvitelli.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.