Abstract 73P
Background
Real-world data on indications of Oncotype DX® testing (RS) and its impact on adjuvant chemoendocrine therapy (CET) use in early-stage BC pN0/1 patient (pt) subpopulations and across multiple French centers are limited.
Methods
We conducted a comprehensive retrospective observational study of BC characteristics, management practices, and therapeutic decision impact of RS results.
Results
952 pts underwent RS testing, including 420 across 2 private clinics (Apr 2014 – Dec 2023), and 505 at Gustave Roussy Institute (Nov 2020 – Dec 2023). Pt characteristics were consistent across private/public centers and were as follows: ≤50y 32.2 %, 51–70y 60.1 %, >70y, 7.7 %; 64.1 % postmenopausal, 35.1 % premenopausal; male 0.8% (n=8). Pathological tumor size, pT1a-b 7.9 %, pT1c 56.2 %, pT2 33.4 %, pT3–4 1.4 %, ypT1c–2, 1.1%; tumor grade 1 13.0 %/ 2 66.6 %/ 3 20.5 %; invasive ductal carcinoma 75.8 %, invasive lobular carcinoma 13.7 %; Ki67 >20%, 49.0 %; pN0 62.7 %, pN1mi 11.4 %, pN1 25.9 %. Retrospective analysis showed that primary reason for testing was for discordant/intermediate histoprognostic factors (73.2 %). Other reasons were the need to confirm endocrine therapy only or CET indication (9.7 %/15.2 %, respectively). Mean test turnaround time was 6.5±2.5 days and was stable over time. As compared to pre-test decisions, RS results led to a 67.6 % reduction in CET use (Table). In pN0 and pN1mi/N1 pts, this reduction was 60.9 % and 78.3 %, respectively. Higher de-escalation rates were observed in pN1mi/N1 pts in most subgroups. Table: 73P
Indications of chemoendocrine therapy before/after RS testing
| CET indication | All pts | ≤50y | 51-70y | >70y | Pre-menopausal | Post-menopausal | Male |
| All pN, n | 941 | 304 | 564 | 73 | 331 | 602 | 8 |
| Pre-test (%) | 89.1 % | 84.9 % | 90.8 % | 93.2 % | 85.8 % | 90.7 % | 100.0 % |
| Post-test (%) | 28.8 % | 38.6 % | 22.5 % | 37.0 % | 38.2 % | 23.9 % | 12.5 % |
| % decrease | -67.6 % | -54.5 % | -75.2 % | -60.3 % | -55.5 % | -73.6 % | -87.5 % |
| pN0, n | 587 | 230 | 321 | 36 | 248 | 334 | 5 |
| Pre-test (%) | 87.1 % | 83.9 % | 88.8 % | 91.7 % | 85.1 % | 88.3 % | 100.0 % |
| Post-test (%) | 34.0 % | 42.2 % | 27.6 % | 38.9 % | 41.1 % | 29.2 % | 0.0 % |
| % decrease | -60.9 % | -49.7 % | -68.9 % | -57.6 % | -51.7 % | -66.9 % | -100.0 % |
| pN1mi/N1, n | 349 | 73 | 239 | 37 | 82 | 264 | 3 |
| Pre-test (%) | 92.6 % | 87.7 % | 93.7 % | 94.6 % | 87.8 % | 93.9 % | 100.0 % |
| Post-test (%) | 20.1 % | 27.4 % | 15.5 % | 35.1 % | 29.3 % | 17.1 % | 33.3 % |
| % decrease | -78.3 % | -68.8 % | -83.4 % | -62.9 % | -66.7 % | -81.8 % | -66.7 % |
Conclusions
RS testing allowed for considerable therapy de-escalation in our cohort, including in specific subpopulations. Our results confirm the test’s utility to refine management strategies and avoid overtreatment in daily clinical practice. Cost-effectiveness will be assessed in a pharmacoeconomic substudy.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
N. Joyon: Financial Interests, Personal, Invited Speaker: Exact Sciences. M. Lacroix-Triki: Financial Interests, Personal, Invited Speaker: Exact Sciences, Myriad Genetics. S. Delaloge: Financial Interests, Institutional, Advisory Board: Novartis, Sanofi, Gilead; Financial Interests, Institutional, Invited Speaker: Pfizer, Roche Genentech, BMS, Sanofi; Financial Interests, Institutional, Advisory Board, ad board: Besins Healthcare; Financial Interests, Institutional, Invited Speaker, ESMO symposium: Gilead; Financial Interests, Institutional, Advisory Board, scientific board: Elsan; Non-Financial Interests, Member of Board of Directors, Société Française de Sénologie et Pathologie Mammaire: SFSPM; Non-Financial Interests, Principal Investigator, H2020 funding: European Commission. J.T.L. Ribeiro Mourato: Financial Interests, Personal, Advisory Board: Exact Sciences. A.A. Viansone: Financial Interests, Personal, Other, Honoraria: Seattle Genetics; Financial Interests, Personal, Advisory Board: Seattle Genetics; Financial Interests, Personal, Other, Speakers' Bureau: AstraZeneca/Daiichi Sankyo; Financial Interests, Personal, Funding, Research funding: Pfizer; Financial Interests, Personal, Expert Testimony: Seattle Genetics; Financial Interests, Personal, Other, Travel, Accommodations, Expenses: Eisai Europe. All other authors have declared no conflicts of interest.