To identify gCIS that occur on multiple backgrounds (i.e., driver non-specific) but fall below the significance threshold in individual cohorts, we combined tumors from Pik3caE545K, Pik3caH1047R, Trp53R270H, K-RasG12D, Notch1ICD, Stat3C, Elf3, and control mice into a single large pan-mammary tumor cohort and repeated gCIS analysis. Here, ELF3 is linked to breast cancer.