Abstract 149P
Background
The 21-gene Recurrence Score (RS) assay is a validated prognosticator/predictor of chemotherapy (CT) benefit in early-stage estrogen receptor (ER)-positive HER2-negative breast cancer (BC). Based on previous retrospective trials, in patients with RS<31, chemoendocrine therapy (CET) was not superior to endocrine therapy (ET) alone. Recent prospective trials confirmed non-inferiority of ET vs CET in patients with RS<26. Data regarding CT benefit in the RS 26-30 group are sparse.
Methods
This exploratory analysis of the Clalit Health Services (CHS) registry included all CHS patients with ER+ HER2-negative BC and RS 26-30 who underwent RS testing between 1/2006 and 12/2016, and determined 7-year Kaplan-Meier (KM) estimates for overall survival (OS), distant recurrence free survival (DRFS), and BC-specific mortality (BCSM).
Results
The analysis included 394 node-negative patients (49% CET-treated, 51% ET-treated) and 140 node-positive patients (62% CET-treated, 38% ET-treated). For node-negative patients, with a median (IQR) follow up of 7.8 (5.8-11.1) years, KM estimates for OS, DRFS, and BCSM were not statistically significantly different between the CET and ET groups; 7-year rates (95% CI) in the CET vs the ET group, were 97.9% (94.4-99.2%) vs 97.9% (94.6-99.2%) for OS, 91.5% (86.6-94.7%) vs 91.2% (86.0-94.6%) for DRFS, and 0.5% (0.1-3.7%) vs 1.6% (0.5-4.7%) for BCSM. For node-positive patients, with a median (IQR) follow up of 8.2 (5.8-11.1) years, KM estimates were not statistically significantly different between the CET and ET groups for OS and DRFS; 7-year rates (95% CI) in these respective groups were 96.3% (89.2-98.8%) vs 93.8% (82.3-98.0%) for OS, and 89.4% (80.9-94.4%) vs 78.0% (64.3-87.5%) for DRFS. The BCSM KM estimates differed significantly between the treatment groups (P=0.024, log-rank test); the 7-year BCSM rate (95% CI) was 1.3% (0.2-8.6%) in the CET group and 6.2% (2.0-17.7%) in the ET group.
Conclusions
In node-negative ER+ HER2-negative BC patients with RS 26-30, CT had no significant effect on clinical outcomes; however, in node-positive ER+ HER2-negative BC patients, CT was associated with a statistically significant reduction in BCSM, without a statistically significant effect on OS and DRFS.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Rotem and Stemmer.
Funding
Oncotest, Exact Sciences.
Disclosure
O. Rotem: Financial Interests, Personal, Invited Speaker: AstraZeneca, Boehringer Ingelheim, BMS, MSD, Novartis, Pfizer, Roche, Takeda, Teva; Financial Interests, Personal, Advisory Role: NucleaiMD, Edocate. I. Kuchuk: Financial Interests, Personal, Invited Speaker: Roche, Pfizer, Medison; Financial Interests, Personal, Sponsor/Funding, Travel support: Roche, Medison, Pfizer. S. Paluch-Shimon: Financial Interests, Institutional, Advisory Board, Advisory board invited speaker honoraria: Roche, Exact sciences, Eli Lilly; Financial Interests, Institutional, Other, Advisory board invited speaker honoraria: Pfizer, Novartis, AstraZeneca; Financial Interests, Institutional, Other, Advisory board, speaker's bureau, consultancy: Medison; Financial Interests, Personal and Institutional, Research Grant, Research grant for an RFP independent research put out by SPCC and Pfizer: SPCC (Shared Progress in Cancer Care). R. Yerushalmi: Financial Interests, Personal, Principal Investigator: Roche, AstraZeneca; Financial Interests, Personal, Invited Speaker: Roche, Novartis, Medison, MSD, AstraZeneca, Eli Lilly; Financial Interests, Personal, Advisory Role: Roche, Pfizer, Novartis, Medison, Gilead Sciences, Eli Lilly, AstraZeneca. A. Sonnenblick: Financial Interests, Personal, Advisory Role: Eli Lilly, Pfizer, Novartis, Roche, Gilead, MSD, AstraZeneca, Progenetics; Financial Interests, Personal, Other, travel/accommodation expensess: Neopharm, Celgene, Medison; Financial Interests, Personal, Other, travel/accommodation expenses: Roche; Financial Interests, Personal, Invited Speaker: Teva, Roche, Pfizer, Novartis, Eli Lilly; Financial Interests, Personal, Research Grant: Novartis, Roche. E. Nili Gal Yam: Financial Interests, Personal, Other, Honorarium: Roche, Novartis, Eli Lilly, Pfizer, MSD, AstraZeneca. H. Goldvaser: Financial Interests, Personal, Other, Honorarium: Roche, Rhenium, Oncotest, Novartis, Pfizer, MSD; Financial Interests, Personal, Advisory Role: Novartis, Pfizer, Eli Lilly, Gilead. A. Bareket-Samish: Financial Interests, Personal, Writing Engagements: Can-Fite, Teva, Rhenium, Exact Sciences, Pfizer. L. Soussan-Gutman: Financial Interests, Personal, Full or part-time Employment: Oncotest, Genomic Health. S. Stemmer: Financial Interests, Institutional, Research Grant: Can-Fite, AstraZeneca, BioLine RX, BMS, Halozyme, Clovis Oncology, CTG Pharma, Exelexis, Geican, Lilly, Moderna, Teva, Roche; Financial Interests, Personal, Stocks/Shares, stocks/options: CTG Pharma, DocBox MD, Tyrnovo, VYPE, Cytora, Can-Fite. All other authors have declared no conflicts of interest.