Discordant Breast Cancer: Genomic vs Clinicopathologic.

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Background: Studies using the 21-gene recurrence score (RS) have shown early-stage, low-risk pathologic and genomic breast cancers do not benefit from systemic chemotherapy (CTx) whereas early stage, high-risk breast cancers have improved outcomes when treated with CTx. Data is lacking for patients with discordant risk factors and which feature, genomic or clinical, plays more of a role in determining outcomes.

Methods: A retrospective analysis was conducted to identify early-stage breast cancer patients with discordant features, defined as low-risk genomic/high-risk pathologic factors (LG/HP) or high-risk genomic/low-risk pathologic factors (HG/LP), from August 2011–December 2016. LG/HP breast cancer was defined as a RS <18 with ≥2 high-risk pathologic factors: tumor size (T) ≥2cm, lymph node (N) positivity, or grade 2-3 disease. HG/LP breast cancer was defined as a RS ≥31 with all three low-risk pathologic factors: T <2cm, N negativity, and grade 1-2 disease.

Results: There were 469 patients with low-risk RS identified of whom 118 (25%) met discordant high-risk pathologic criteria and 62 patients with high-risk RS of whom 14 (23%) met discordant low-risk pathologic criteria. Thirty patients in the LG/HP group received CTx despite a low RS. Of the 118 LG/HP patients, there were 22 (19%) breast cancer recurrences; 21 with locoregional and one with metastatic disease. Of the locoregional recurrences, 10 were contralateral breast whereas 11 were in-breast recurrence despite breast conservation therapy. Of the 14 HG/LP discordant patients, of whom 12 received CTx, 3 (21%) had breast cancer recurrence; one with metastatic disease to the lung and the other two with contralateral breast cancer. Majority of all recurrences occurred >5 years after initial diagnosis. Staging and management depicted below.


San Antonio Breast Cancer Symposium, San Antonio, TX, December 5-9, 2017.