We examined the correlation in gene expression of the core polarity proteins together as well as in relation to PRLR gene expression in the Sweden Cancerome Analysis Network-Breast (SCAN-B) database (GSE202203) containing a large RNA-Seq dataset of 3207 breast cancer patients, making it one of the most extensive population-based cohorts of primary breast tumors to date. This evidence concerns the gene PROS1 and breast carcinoma.