Substantial Reduction in Adjuvant Chemotherapy With the Use of the 21-Gene Test to Manage Early Breast Cancer in a Public Hospital in Brazil.

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.
Competing Interests: André MattarEmployment: Novo NordiskStock and Other Ownership Interests: Novo NordiskHonoraria: DASAConsulting or Advisory Role: Lilly, AstraZeneca, Roche, Novartis, Fleury Group, Exact SciencesSpeakers' Bureau: Exact Sciences, NovartisOther Relationship: Genomic Health, Roche Debbie M. JakubowskiEmployment: Exact SciencesStock and Other Ownership Interests: Exact Sciences Calvin ChaoEmployment: Exact SciencesLeadership: Exact SciencesStock and Other Ownership Interests: Exact Sciences Sergio C. OliveiraEmployment: Exact SciencesTravel, Accommodations, Expenses: Exact SciencesNo other potential conflicts of interest were reported.