Abstract
BackgroundThe existence of oestrogen receptor-negative (ER−)/progesterone receptor-positive (PR+) breast cancer continues to be an area of controversy amongst oncologists and pathologists.MethodsTo re-evaluate breast cancers originally classified as ER−/PR+ via Oncotype DX® assay and compare molecular phenotype with Recurrence Score® (RS) result, clinicopathologic features and clinical outcomes were retrospectively obtained from electronic health records between January 1998 and June 2005. Archived formalin-fixed, paraffin-embedded (FFPE) tumour specimens were tested for the expression of ER, PR and human-epidermal-growth-factor-2. The number of positive ER−/PR+ samples confirmed by transcriptional analysis was the primary outcome of interest with event-free and overall survival as secondary outcomes. Biopsies from 26 patients underwent Oncotype DX testing and analysis.ResultsApproximately 60% were middle-aged (40–50 years old) women, and 84.6% had invasive ductal carcinoma. Based on the Oncotype DX assay, approximately 65% (N = 17) had ER+/PR+ status; 23% (N = 6) had ER−/PR− status; and 12% had a single hormone positive receptor (1 ER–/PR+, 2 ER+/PR–) status. Almost one-quarter of patients were stratified into the low-RS (<18) or intermediate-RS (18–30) results, and half of the patients had a high-RS (>30) result.ConclusionOur findings suggest the ER−/PR+ subtype is not a reproducible entity and emphasises the value of retesting this subtype via molecular methods for appropriate treatment selection and patient outcomes. Multigene assay analysis may serve as a second-line or confirming tool for clinical determination of ER/PR phenotype in breast cancer patients for targeted therapies.
Highlights
Breast cancer is not one disease but comprises a heterogeneous disease group of a growing number of biological subtypes that have diverse natural histories and responsivenessPublished: 24/08/2021 Received: 01/07/2021Publication costs for this article were supported by ecancer (UK Charity number 1176307).Copyright: © the authors; licensee ecancermedicalscience
Of the hormone receptors (HRs), ER expression is predictive in identifying tumours that will respond to endocrine therapy, whereas progesterone receptors (PR) expression is prognostic with patients exhibiting PR− breast cancers having poor outcomes [2,3,4]
By re-examining the phenotype and associated patient outcomes of breast cancer biopsies previously designated as ER−/PR+ with updated techniques, our results suggest that ER−/PR+ tumours are not a reproducible pathological entity, though small sample size precludes definitive conclusions regarding the existence or non-existence of this subtype
Summary
Determination of appropriate breast cancer treatments and prognostic outcomes are dependent on the accurate histologic classification and measurement of two main biomarker groups: hormone receptors (HRs; including oestrogen (ER) and progesterone receptors (PR)) and human epidermal growth factor 2 (HER2) [1]. Endocrine therapy is considered the most effective treatment to downregulate ER-related cancer cell functions with relatively low toxicity compared to cytotoxic chemotherapy in patients with ER+ breast cancer [1]. The existence of oestrogen receptor-negative (ER−)/progesterone receptor-positive (PR+) breast cancer continues to be an area of controversy amongst oncologists and pathologists
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
