Our findings implicate the GPER/HIF‐1A axis as a master regulator of peri‐tumoral stromal remodeling and the fibrovascular tumor microenvironment and offer a paradigm shift for tamoxifen from a well‐established drug in breast cancer hormonal therapy to an alternative candidate for stromal targeting strategies in PDAC and possibly other cancers. This evidence concerns the gene GPER1 and breast carcinoma.