In the test set, tumors were more often detected by mammography screening (61 vs 58%; P = 0.003, V = 0.022), there was a slightly lower frequency of invasive lobular carcinoma (ILC) (12 vs 13%; P < 0.001, V = 0.018), and the progesterone receptor (PgR) expression was lower (58.0 vs 59.9%; P = 0.007, d = -0.047). This evidence concerns the gene PGR and invasive lobular breast carcinoma.