Finally, the LASSO regression analysis identified the following 13 most powerful factors: the age group, clinical tumour stage, histologic type, number of positive SLNs, number of negative SLNs, number of SLNs dissected, SLN metastasis ratio, ER status, PR status, HER2 status, Ki67 staining percentage, molecular subtype and P53 status (Fig. 1). This evidence concerns the gene PGR and neoplasm.