Discordant breast cancer: Low risk genomic, high risk pathologic.

Abstract

e18160 Background: Studies using the 21-gene recurrence score (RS) have shown low risk pathologic features and RS breast cancers do not benefit from systemic chemotherapy (CTx). However, data is lacking for patients with discordant risk factors and which feature, genomic or clinical, plays more of a role in determining outcomes. Methods: Retrospective analysis was conducted to identify breast cancer patients with discordant features, defined as low genomic/high pathologic factors, from 2011 to 2016. Patients were hormone-receptor positive with RS < 18 and had ³ 2 high risk factors: tumor size ³2cm, lymph node (LN) positivity, or grade 2-3 disease. Results: There were 469 patients with low risk RS were identified of whom 118 met discordant risk criteria. Patients management is depicted in Table 1. Of the 118 discordant patients, 22 had breast cancer recurrence as either metastatic (1) or locoregional (21); 11 being ipsilateral while the remainder were contralateral. Patients with ipsilateral recurrences had partial mastectomy and radiotherapy as initial management. CTx was received in 30 patients despite low RS. Recurrences occurred in 31.8% of patients who received adjuvant CTx. The majority of recurrences occurred >5 years after initial diagnosis. Conclusions: Our results show both genomic and pathologic features were important in determining the need for CTx in early stage breast cancer but neither had a greater impact. Thus, we advocate a more comprehensive and individualized approach, taking into account comorbidities, genomic, and pathologic features, for addition of CTx to standard hormonal therapy. Further studies are needed to determine the proper treatment of this unique patient population. [Table: see text]