Notably, significant enrichment of IRS2 was exclusive to BM from CRC and was not observed in BM from other primary tumors when compared to their local tumors, including lung cancer (0.8% vs 0.6%, P = 0.4), breast cancer (2.6% vs 1.5%, P = 0.1), and melanoma (0.2% vs 0.3%, P = 1) (Supplementary Table S9). The gene discussed is IRS2; the disease is breast cancer.