250PThe concordance of treatment decision guided by oncotype and the PREDICT tool in early stage breast cancer

Abstract Background Decision on adjuvant chemotherapy for early breast cancer can be guided by genomic assays. PREDICT is a validated free online tool that estimates the benefit from adjuvant chemotherapy using clinical and pathological data. The concordance of expected clinical decisions guided by Oncotype analysis and the PREDICT in unknown. Methods A retrospective single center cohort study comprising all women with estrogen receptor (ER) positive, human epidermal growth factor receptor 2 negative, node negative disease, whose tumors were sent for OncotypeDX analysis. Estimation of 10-year overall survival (OS) benefit from 2nd generation chemotherapy was calculated using the PREDICT 2.1v tool. Omission of chemotherapy was expected to be advised when Oncotype recurrence score (RS) was ≤25 or when the estimated 10-year OS benefit by the PREDICT was  25 and estimated PREDICT benefit ≥2%. Concordance was presented using percentages and the K coefficient. The impact on concordance of pre-specified histological features was assessed, including tumor size, intensity of ER and progesterone receptor (PR), grade, Ki67 and perineural and lymphovascular invasion. The difference between the subgroups was calculated using Chi-squared test. Results A total of 445 women were included. Overall concordance was 75% (K = 0.284), with 55 (12.5%) women with low RS but estimated PREDICT benefit ≥2% and 55 (12.5%) with high RS and estimated PREDICT benefit  1cm (85% vs 72%, p = 0.009), PR positive compared to PR negative (78% vs 58%, p  Conclusions Compared to PREDICT, using Oncotype in node negative, ER positive disease is expected to change clinical decision in a quarter of patients. The concordance is influenced by pathological features. The use of Oncotype may not be necessary for clinically very low risk patients. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure H. Goldvaser: Honoraria (self): Roche. R. Yerushalmi: Honoraria (self): Roche; Honoraria (self): Medison; Honoraria (self): AstraZeneca; Honoraria (self): Novartis; Honoraria (self): Teva. M. Sarfaty: Honoraria (self): Roche; Honoraria (self): MSD; Honoraria (self): Medison; Honoraria (self): Novartis. All other authors have declared no conflicts of interest.