Abstract P2-08-21: Outcomes results of Prosigna® test in early breast cancer patients: Experience of Institut Curie, France

Abstract

Abstract Prosigna® tests are performed in Institut Curie to guide adjuvant chemotherapy decision in early estrogen receptor (ER) positive, Human Epidermal growth factor Receptor (HER2) negative breast cancer (BC) patients, with an intermediate risk of recurrence. The objective of this study was to check the absence of an early warning signal for therapeutic decisions guided by the use of genomic tests in terms of the occurrence of events during the follow-up. Methods: Follow-up analysis were made on 2 populations: Real-life population: ER positive, HER2 negative BC patients who had a Prosigna® test in clinical routine, were prospectively registered and their data collected. Prosigna® test was indicated for patients with an intermediate risk of recurrence defined by our regional guidelines (1): grade 1 T1cN1, grade 1 T2N0-1, grade 2 T1cN0 with pejorative prognosis parameters (Ki67>20% or lympho-vascular emboli), grade 2 T2N0, grade 3 T1cN0. Decision impact (DI) study (2): a prospective multicenter study evaluating the decision impact of Prosigna® tests on adjuvant chemotherapy treatment. All consecutive T1-T2 NO-N1(mic) ER positive, HER2 negative BC patients were included. Survival was estimated by Kaplan-Meier methods and compared between patients who received or not chemotherapy based on the tests results with a Log-rank test (chemotherapy was administered for patients with a 10-years distant recurrence probability >=10%). Results are given in % with 95% intervalley confidence. Results: 647 patients were included (124 from DI study and 523 from clinical routine). Median age was 59 years-old (28-83). The median size of the tumor was 17 mm, (3-75), with a majority of grade 2 tumors (n=473, 73%) and 14% of lymph node involvement (n=90). Prosigna® tests results showed: 54% of luminal A.; respectively 30% (n=195), 40% (n=257) and 30% (n=195) of high, intermediate and low risk categories. The median 10-years distant recurrence probability was 10% (2-45%). The median follow-up of the patients was 18 months (0-52). We did not observe death in our study population, and we registered 10 recurrences (4 distant-DMFS- and 6 locoregional-LDFS). Disease free survival (DFS) at respectively 12 and 24 months were 99.8% (98.9-100) and 98.6% (96.5-99.4). Locoregional DFS at 12 and 24 months were 99.8% (98.9-100) and 99.2% (97.4-99.8) and distant DFS at 12 and 24 months were 100% and 99.4% (97.5-99.8). We did not observe survival differences between patients treated by chemotherapy and hormone therapy (CT) and patients treated by hormone therapy alone (No CT). DFS were respectively for CT and no CT groups 99.6% (97.4-99.9) and 99.5% (96.8-99.9, p=0.8) at 12 months, and 98.9% (95.1-99.7) and 99% (96-99.7, p=0.8) at 24 months. Distant and locoregional DFS were also not different between CT and No CT groups. Discussion: The first results of this study, mainly composed of clinical routine patients, are totally reassuring. We did not identify early warning signal in terms of survival with the use of Prosigna® test to guide adjuvant chemotherapy decisions in early BC patients at intermediate risk of recurrence. Moreover, our results are in accordance with the TAILORx (3) and MINDACT (4) randomized prospective studies survivals.