Abstract P3-14-05: Oncotype DX assay’s real world data in early stage breast cancer patients. Outcomes of a cohort treated in the Basurto University Hospital, Spain

Abstract

Abstract Introduction: Oncotype DX (ODX) Recurrence Score (RS) is a gene-expression assay that provides prognostic and predictive information in hormonal-receptor positive (HR +), human epidermal growth factor receptor 2 negative (HER2-), axilary lymph node negative (LN-) disease. It estimates the 10 year-risk of distant recurrence and it is recommended to asses this issue and the potential benefit of adjuvant systemic therapy in early stage breast cancer (ESBC). (JCO 2016, NCCN 2019). Objective: To evaluate the impact of RS on our adjuvant treatment decision making and follow-up (FU). Materials and methods: Observational, prospective single institution study. Eligible patients (pts) were diagnosed between September 2012 and December 2018 with HR+, HER2 -, N0 and N+ (N1mic) ESBC for who underwent ODX assay. Criteria for ordered ODX assay were established by the group of experts from the Basque Country Health System. Treatment recommendations were documented before and after the conventional RS results. We reviewed clinical and pathology reports for FU and events. Descriptive statistics were used to summarize patient and tumor characteristics and changes in oncologists’ treatment recommendations. Mc Nemar’s test was used to identify how these tests impact in decisión. Results: N=337 pts. Median age was 57 years (SD 9,11); women 328 pts (97%); premenopausical 114 (34%); conservative surgery 271 pts (80%); sentinel node 318 pts (94 %); pN0: 248 pts (74%), pN1mic: 89 (26%); tumor size: pT1a-b: 41 pts (12 %), pT1c: 234 pts (69%) and pT2: 62 pts (18%); histologic type: ductal 280 pts (83%); histological grade: G1 49 pts (16%), G2 250 pts (74 %), G3 34 pts (10%); Ki 67 index >=13: 221 pts (66 %); progesterone receptors: positives: 304 pts (90%); presence of lymphovascular invasión:36 pts (11%). Treatment decision before assay was hormonal therapy (HT) in 242 pts (72 %) and chemotherapy (CT) in 95 pts (28 %). Conventional RS were: low risk RS<18 (LR): 180 pts (53%), intermediate risk RS 18-30 (IR): 135 pts (40%) and high risk RS >30 (HR): 22 pts (7%). TAILORx RS cutpoints were: LR RS <11: 78 pts (23%), IR RS 11-25: 207 pts (61%), HR RS >25: 52 pts (15%). Post-assay treatment: 278 pts (82.5%) received HT and 59 pts (17.5 %) CT. Treatment recomendation pre and post ODX assay changed in 17,5% of pts: in 10,5% from CT to HT and 7% from HT to CT. The McNemar's test was significant value (0.000). With a median FU of 35 months (range 1-77) there were 5 events: (1.5%): 1 local (0.3%) and 4 distant (1.2%). Conclusions: In our cohort, the 82.5% of pts received HT. The treatment decisión changed 17.5% of pts. The ODX avoided CT in 10.5% of 38 pts (28% pre and 17.5% post). At this time, insufficient median FU and number of events are available to examine long-term prognosis and CT benefit. Citation Format: Maria Purificacion Martínez del Prado, Borja López de San Vicente, Juan Fernando Arango Arteaga, Jairo Legaspi Folgueira, Ane Zumárraga Cuesta, Fernando Pikabea Diaz, Patricia Novas Vidal, María López Santillán, Laura Sande Sardina, Maitane Nuño Escolástico, María Teresa Abad Villar, Maria Ángeles Sala Gonzalez, Covadonga Figaredo Berjano, María Teresa Pérez Hoyos, Elena Galve Calvo. Oncotype DX assay’s real world data in early stage breast cancer patients. Outcomes of a cohort treated in the Basurto University Hospital, Spain [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-14-05.