PURPOSE We evaluated the impact of 21-gene test results on treatment decisions for patients with early-stage breast cancer treated under the public health care system in Brazil, Sistema Único de Saúde. METHODS Eligible patients treated at Hospital Pérola Byington and Santa Casa de Misericórdia de São Paulo in Brazil were required to have the following characteristics: postsurgery with hormone receptor–positive, human epidermal growth factor 2–negative, node-negative and node-positive, and T1/T2 breast cancer and patients with these characteristics were candidates for adjuvant systemic therapy. Treatment recommendations, chemotherapy plus hormonal therapy (CT + HT) or HT alone, were captured before and after 21-gene test results. RESULTS From August 2018 to April 2019, 179 women were enrolled. The mean age was 58 years (29-86 years), 135 (76%) were postmenopausal, and 58 (32%) had node-positive breast cancer. Most patients (61%) had a tumor > 2 cm, including 7% with tumors > 4 cm. Using Recurrence Score (RS) result cut points on the basis of the TAILORx trial, 40 (22%) had RS 0-10, 91 (51%) had RS 11-25, and 48 (27%) had RS 26-100. Before 21-gene testing, 162 of 179 (91%) patients were recommended for CT. After testing, 117 of 179 patients (65%) had changes in CT recommendation: 112 (63%) who were initially recommended CT received HT alone and five (3%) who were initially recommended HT alone received CT + HT. After 21-gene testing, 99% of physicians reported strong confidence in their treatment recommendations. CONCLUSION The change in clinical practice at these public hospitals was greater than expected: 66% of initial treatment recommendations were changed to omit CT with 21-gene test results. Clinicopathologic features did not correlate well with 21-gene test results and did not adequately identify those most likely to benefit from CT.

e12518 Background: The 21-gene assay estimates risk of recurrence expressed as a Recurrence Score result between 0 and 100. The assay is clinically validated to predict chemotherapy (CT) benefit in node-negative (N0) and node-positive (up to three axillary nodes, N1) hormone receptor-positive (HR+) early-stage breast cancer (ESBC). The TAILORx study, which randomized 6711 women with N0 ESBC and Recurrence Score result 11-25 to hormonal therapy (HT) ± CT, demonstrated that patients older than 50 years derived no benefit from CT+HT, although younger patients with Recurrence Score result 16-25 may derive some benefit. The 21-gene assay has been incorporated in practice guidelines worldwide, based on evidence of clinical utility in N0 and N1 ESBC. We evaluated the impact of the 21-gene test on treatment decisions for patients with N0 and N1 ESBC at Sistema Único de Saúde in Brazil. Methods: Eligible patients were post-surgery with T1/T2 tumors, had HR+, HER2−, N0 or N1 ESBC, and were candidates for adjuvant systemic therapy. Treatment recommendations, CT+HT or HT alone, were captured before and after 21-gene test results. All patients were seen at Pérola Byington Hospital, a public hospital in São Paulo, Brazil. TAILORx results were used to guide decisions for or against CT for each patient. Results: From 08/2018 to 04/2019, 155 women were enrolled. Patient mean age was 57.6 years (29-78), 116 (75%) were postmenopausal, and 53 (34%) had N1 breast cancer. Based on clinical data alone, 151 patients had pre-assay recommendations of CT. Post-assay, 106 of 151 patients (70%) had changes in CT recommendation: 104 (69%) initially recommended CT received HT alone, and 2 (1%) initially recommended HT alone received CT+HT (Table). Using the modified Adjuvant!Online criteria for clinical risk classification, 109 of 155 patients (70%) had high risk, 48 (44%) of whom received CT. Of 46 patients with low clinical risk, 10 (22%) received CT. CT use trended with histologic grade: 11% with grade 1, 69% with grade 2, and 61% with grade 3. Most of our patients had tumor bigger than 2 cm (61%) with 8% bigger than 4 cm. Conclusions: The change in clinical practice at this public hospital was greater than expected: 69% of initial treatment recommendations were changed with the Recurrence Score result to omit CT. Clinicopathologic criteria did not correlate well with Recurrence Score results and did not identify those most likely to benefit from CT. A cost-effectiveness study is underway at our institution. [Table: see text]

e19380 Background: Selecting appropriate patients for AC (adjuvant chemotherapy) remains an important issue in BC treatment. Although AC improves clinical outcomes toxicity and economic burden is substantial. The Oncotype DX test identifies high-risk patients likely to benefit from AC who otherwise might not be identified through standard parameters (SP), and low-risk patients unlikely to benefit from AC, avoiding toxicities and inherent risks. This study estimated the incremental cost-effectiveness ratio and budget impact (BI) of Oncotype DX testing from the perspective of the Brazilian Public Health System. Methods: A Markov transitional state model was developed with 3 states: recurrence free, distant recurrence, and death. The model compared the scenario in which patients are screened by SP with a proposed scenario with Oncotype DX testing. Changes in therapeutic recommendations and cost of treatment were obtained from a prospective clinical survey at Pérola Byington Hospital. Additional data was obtained from literature. As a societal perspective analysis, medical costs (test, AC, and adverse events), costs of productivity loss, transportation and employment leave were considered. Population was estimated from BC incidence, proportion of early stage cases, and HR expression. An incremental proportion of 10% per year of patients using Oncotype DX testing was assumed. BI analysis had a 5-year horizon and cost-effectiveness a lifetime horizon (5% annual discount). Results: Oncotype DX results as identifier of a subgroup at higher risk of relapse and greater benefit with AC was dominant over SP. Oncotype DX testing resulted in clinical benefits in terms of life-years gained (0.62) and quality-adjusted life years (0.54), related to lower incidence of distant recurrence and use of AC, both of which greatly impacted quality of life. Testing resulted in economic benefits, with lower average cost per patient (−BRL 3,855). Incorporation of Oncotype DX testing resulted in potential savings reaching BRL 107 million in the 5th year stemming from the decrease in AC and consequent decrease in indirect costs. Conclusions: Patients with HR+, HER2− early stage BC may present different risks of relapse and likelihoods of benefiting from AC. With high clinical impact for patients and high economic impact for the health system, a tool that safely and accurately identifies the subgroup of patients who really needs AC is essential. Oncotype DX test incorporation in the Brazilian Public Health System should be considered.