209PInfluence of age on the indication of adjuvant chemotherapy in early breast cancer using Oncotype DX. An analysis of 240 patients treated in the Institut Catala d’Oncologia (ICO) hospitals

Abstract Background Benefit derived from adjuvant chemotherapy (CT) is doubtful in a high percentage of patients (pt) with hormone-receptor–positive HER2 negative early breast cancer. The 21-gene recurrence-score (RS) assay Oncotype DX, provide prognostic and predictive information. Results of the TAYLORx study have confirmed that most of patients with negative node status and RS > 25 can avoid CT without increasing their risk of relapse. However, pt   20 showed benefit with CT. Methods Aim: To analyse the impact of age using RS test to change the indication of adjuvant CT and the relationship between different clinical pathological factors and the RS value. We analysed 240 cases out of 251 RS test performed in the 3 ICO Centers during 2017-2018. We compared the adjuvant treatment initially planned according to institutional protocol with the treatment given after RS in the total cohort and in pt  Results CT was indicated in all pt before knowing the RS results. Only 46 pt (19%) received CT after RS results. 14 out of 88 pt 25 (  25 in a multivariate analysis. Table . 209P Age median (range) 53 (19-76) Tumor size median 15 mm Histological grade G1 23% G2 69.7% G3 4.4% Progesterone receptor ≤20% 21% >20% 78% Ki67 median (p25-75) 20 (13,28) ≤14 27% 14-25 41% >25% 31% Nodal status pN0 57% pN1mic 15% pN1a 27% Conclusions 82% of pt of our series could avoid CT, however this proportion change after TAYLORx results in younger patients. Today 75% of these pt would had avoided CT. Ki67 > 25% and Progesterone Receptor ≤20% were the only pathological factors associated with an increased risk of RS > 25. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.