Abstract P5-15-09: Impact of oncotype dx genetic signature used in early breast cancer. Clinical and economic analisys of a 110 patient cohort treated in the Catalan Oncologic Institute (ICO), Spain

Abstract

Introduction Benefit from adjuvant chemotherapy (CT) is doubtful in a high percentage of patients with early breast cancer. The 21-gene recurrence-score (RS) assay (Oncotype DX, Genomic Health) is one gene-expression assay that provide prognostic and predictive information in hormone-receptor (RH) positive breast cancer. The results of the TAILORx study have confirmed that the majority of patients with tumors RH + and HER2 negative can avoid CT without increasing their risk of relapse. From 2012 to 2015 we used Mammaprint (MMP), in our institution and 60% of cases could avoided CT (communicated in SABCS 2015). Since 2017 we use RS for this purpose. Primary Objective To analyze the impact of using RS to change the indication of adjuvant CT. Secondary Objectives To analyze the association between different clinical pathological factors and the RS value, and calculate the difference between the cost of all RS test and the cost in direct expense of the treatment with CT of all patients who could avoid it thanks to the RS Material and methods We analyzed all RS test performed in the three ICO centers during 2017. We sent 112 tumor samples; in 2 samples adequated RNA for RS was not obtained. We compared the adjuvant treatment initially planned according to institutional treatment protocol with the treatment given after RS. We compared the direct economic costs of CT with the costs of the diagnostic test, and performed a logistic regression analysis of some pathological factors and RS value. Results The RS could be determined in 110 of 112 cases, in which there was indication of adjuvant CT. Only 14 patients received CT (12,72%) with the RS value, so CT was avoided in 96 patients (87,28%). The clinical-pathological characteristics of the series are summarized in the table 1. Of the risk factors analyzed, only grade 3 (p 0.001) and PR <20% (p<0.002) showed a statistically significant relationship with a higher probability of RS> 25. No association was found between age, nodal status, tumor diameter, Ki67, Infiltrating Ductal Carcinoma vs neither Infiltrating Lobular Carcinoma nor Lympho-Vascular invasion. The cost of the genetic studies was 180000€ (1636€ each). The cost of each CT schedule (EC x 4 followed by paclitaxel x 12) was 7214€ and the total cost of 96 cases 692590€. Direct costs savings estimated from the reduction in CT treatment were 512590€ Conclusion: Our series shows that RS avoided unnecessary CT in 87% of cases and was more cost-effective than a previous series with MMP. G3 and RP <20 were the only pathological factors associated with an increased risk of RS> 25. Table 1.Patients characteristics and clinical-pathological details from the analyzed tumorsPatient characteristicsAge, mean (range)53,76 (19 – 75)≥50y72 (65.5%)<50y38 (34.5%)HistologyInfiltrating ductal carcinoma88 (80%)Infiltrating lobular carcinoma20 (18,2%)Others2 (1,8%)TNMTumor diameter (mm), mean (range)19,25 (1 – 160)pN058 (52,7%)pN1mic21 (19%)pN131 (28,3%)Hormone receptorsRE 2-100%110 (100%)RP <20%22 (20%)RP ≥20%88 (80%)Ki67 median, mean (range)20, 21 (2-75)Lymphovascular invasionyes9 (8%)no101 (92%)Adjuvant treatmentCT14 (12,72%)Hormonotherapy96 (87,28%) Citation Format: Ferrer M, Dorcas J, Quiroga V, Margelí M, del Barco S, Stradella A, Petit A, Falo C, Viñas G, Romeo M, Villanueva R, Cirauqui B, Vázquez S, Fernández A, Recalde S, Vethencourt A, Soler T, Pérez-Martín X, Gil-Gil M. Impact of oncotype dx genetic signature used in early breast cancer. Clinical and economic analisys of a 110 patient cohort treated in the Catalan Oncologic Institute (ICO), Spain [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-15-09.