Indeed, the positivity rate of ER and/or PgR in LCIS is higher than in DCIS [9], and the results of the former NSABP P-1 prevention study showed that the most effective reduction of invasive BC by tamoxifen was observed among women with LCIS and ALH, suggesting a possible increased impact of anti-estrogens in the first steps of breast cancerization [40]. Here, PGR is linked to breast cancer.