H&E sections from each block were reviewed by a pathologist (TON). Areas containing representative invasive breast carcinoma were selected and circled on the source block. Using a 1.0 mm punch needle, at least two tumor cores were extracted from the circled area. Details of RNA preparation from paraffin cores, the qRT-PCR assay for the PAM50 panel and reference genes, and how these results allow assignment into Luminal A, Luminal B, HER2-enriched and Basal-like subtypes, and the independently-trained ROR-S (Risk Of Relapse based on Subtype), ROR-T (-Tumor size weighted model), ROR-P (-Proliferation weighted model) and ROR-PT (Proliferation and Tumor size weighted) risk score assignments are presented in Supplementary Methods. For clarity, the term ROR-T is now used for the same model described in our earlier publication as ROR-C (“clinical”) (9 (link)).