The use of clinical impact of the breast cancer intrinsic subtype-Prosigna assay for adjuvant treatment decision in early breast cancer with hormone receptor positive and HER-2 negative Middle East women.

Abstract

e12527 Background: Clinico-pathological evaluations of intrinsic subtypes by immunohistochemistry (IHC) are routinely used for treatment decision in patients with early-stage breast cancer (EBC). The Prosigna (PAM50) gene signature, is validated test measures the expression levels of 50 genes from formalin-fixed paraffin-embedded (FFPE) tumor samples. It permits intrinsic subtype classification of tumor and prognostic test of risk of recurrence (ROR) score. The objectives of this study were to evaluate the impact of Prosigna results on type of adjuvant treatment in EBC, to overcome disparities by comparing the results on different ethnicity groups in Israel and to asses physicians treatment decision before and after Prosigna results. Methods: This prospective, observational study was carried out in 7 Medical Centers at Northern Israel. Postmenopausal women with hormone-receptor–positive, human epidermal growth factor receptor 2 (HER2)–negative invasive EBC were enrolled. Physicians completed treatment confidence questionnaires prior to and after receiving Prosigna test results. Only EBC : T 1-2, N0 and N1 were included. Results: Between May 2018 and April 2021, 238 women were enrolled, 204 patients are eligible for this analysis. Ashkenazi Jews were 38%, Sephardi Jews 32% and 30% were Palestinian Arab women. Mean age was 65.28 years. T1 was diagnosed in 82.3%, T2 in 17.3% and N1 in 22.4% of pts. At time of diagnosis tumor subtypes were categorized based on IHC as Luminal A in 50%, 54.4%, 59.5% and Luminal B in 50%, 44.6% and 40.5% of Sephardi, Ashkenazi and Arab patients retrospectively. Intrinsic tumor subtypes detected by the Prosigna test were Luminal A in 63.8%, 71%, 74.3% and Luminal B in 34.5% (+1.7% basal like), 29% and 25.7% respectively. No significant different between these groups. Overall 50.5% of pts were low risk, 26% intermediate risk and 23.5% high risk due to Prosigna results. Following Prosigna results 23.4% of the physicians changed their treatment recommendation. Conclusions: To our knowledge this is the first study using Prosigna test in Middle East women with early breast cancer. The use of Prosigna results led to a 23.4% change in adjuvant treatment decision. The results of this prospective study is similar to the data published in other studies in the literature. The intrinsic tumor subtypes and risk of recurrence detected by Prosigna adds to the physicians' confidence in the choice of treatment type. Prosigna test was additive for understanding the biology and for adjuvant treatment choice in both Jewish and Palestinian women in Israel.