289P - A Study of the Impact of the 21-Gene Breast Cancer Assay on the Use of Adjuvant Chemotherapy in Women With Breast Cancer in a Mexican Public Hospital

Abstract

ABSTRACT Background The majority of early stage breast cancer patients in Mexico are treated through the public health system, and >80% are treated with chemotherapy (CT). The 21-gene assay (Oncotype DX®) is available in Mexico but has been utilized primarily within the private health system. There are no data that describe the potential impact of the assay on adjuvant treatment decision-making for public sector patients. The aim of this study is to characterize how assay results impact the decision-making process and confidence of public sector physicians in Mexico to determine adjuvant therapy. This is the first decision impact study of the Oncotype DX assay in Latin America. Methods At total of 98 consecutive patients with ER + , HER2-, stage I-IIIa, N0/N1-3 breast cancer from the Instituto Nacional de Cancerologia in Mexico City, Mexico, were enrolled in the study. Via consensus discussion in multidisciplinary team meetings, physicians completed pre- and post-assay questionnaires regarding adjuvant treatment recommendations for each enrolled patient. The primary endpoint was the overall change in physician treatment recommendations resulting from the addition of the Recurrence Score® result in the decision-making process. Results Pre- and post-assay results were available for 96 patients. Treatment decisions changed for 31/96 (32%: 95% CI 23%-43%) patients; 17/62 (27%; 95% CI 17%-40%) N0 and 14/34 (41%; 95% CI 25%-59%) N1-3 patients. Post-assay, 8/50 (16%) of patients initially recommended hormonal therapy (HT) were recommended chemohormonal therapy (CHT) or CT, and 21/46 (46%) of patients initially recommended CHT/CT were recommended HT alone. The proportion of patients recommended CT decreased from 48% pre- to 34% post-assay (p = 0.024), a decrease of 14% overall, 6% in N0, and 26% in N1-3 patients. Conclusions These results suggest that use of the 21-gene assay in the Mexican public health system has an impact on adjuvant treatment recommendations and may reduce the use of chemotherapy. Post-Assay Pre-Assay Adjuvant Therapy HT alone CT + HT CT alone Total HT alone 42 (44%) 7 (7%) 1 (1%) 50 (52%) CT + HT 21 (22%) 23 (24%) 2 (2%) 46 (48%) Total 63 (66%) 30 (31%) 3 (3%) 96 Disclosure C. Yoshizawa: Genomic Health- Employment and Stockholder. E. Burke: Genomic Health- Employment and Stockholder. C. Chao: Genomic Health- Employment and Stockholder. All other authors have declared no conflicts of interest.