We also performed an analysis for the progression-free interval after diagnosis of BM and the time from diagnosis of ECM to BM according to breast cancer subtype and found that TNBC patients had the shortest progression-free interval since the first diagnosis of BM of 4.3 months, followed by Luminal A subtype with 5.2 months, HER2 positive subtype with 9.1 months and Luminal B/HER2 enriched subtype with 11.4 months (Table S2, Figure S2). The gene discussed is ERBB2; the disease is breast cancer.