Comprehensive transcriptomic profiling to identify breast cancer patients that may be spared adjuvant systemic therapy.

Abstract

535Background: Some women with early stage breast cancer (BC) may not require additional systemic therapy after breast-conserving surgery (BCS). While this subgroup of ultra low-risk women has been difficult to identify with conventional clinical metrics, transcriptomic profiling may offer improved risk stratification. Previously described genomic signatures perform well on the group level, but reports indicate that there may be substantial disagreement between signatures for an individual patient. Methods: We analyzed tumors from 765 patients in the SweBCG91-RT trial, which randomized node-negative BC patients to +/- radiation following BCS, with minimal use of adjuvant systemic treatment (9%). Median follow-up was 18.6 years for breast cancer-specific survival (BCSS). The original study demonstrated a benefit from radiation on locoregional events, but not BCSS. Tumors were profiled with the Affymetrix Human Exon 1.0 ST microarray and 14 genomic signatures from literature (including Mammaprint-like, Onco...