Impact of biomarkers and genetic profiling on breast cancer prognostication: A comparative analysis of the 8th edition of breast cancer staging system

: The 8th edition of the American Joint Committee on Cancer (AJCC) staging guidelines combine traditional TNM system with biomarkers to reflect our current understanding of tumor biology and targeted therapy. In this study, we investigated the impact of the TNM + Biomarkers staging system and the additive value of Oncotype Dx™ genomic profile recurrence score (RS) (TNM + Biomarkers+RS <11) for the staging of breast cancer (BC) using data from two tertiary referral cancer centers. Compared to TNM alone, the TNM + Biomarkers system changed the stage group in 32.7% of BCs (27% downstage, 5.7% upstage). Most (98.3%) of the downstaged BCs were estrogen receptor (ER)+/progesterone receptor (PR)+, whereas 78% of the upstaged BCs were ER-/PR-/human epidermal growth factor receptor 2 (HER2)-. Compared to TNM + Biomarkers staging, the addition of genetic profile data (TNM + Biomarker+RS <11) downstaged only <1% BCs. Our analysis suggests that for T1-T2N0 ER+/HER2- BCs, Oncotype Dx™ RS <11 provides added value as a staging parameter only in a very small group of cases compared to TNM + Biomarkers alone.