6 Tworoger Tworoger SS SS Eliassen Eliassen AH AH Zhang Zhang X X Qian Qian J J Sluss Sluss PM PM Rosner Rosner BA BA Hankinson Hankinson SE SE A 20-year prospective study of plasma prolactin as a risk marker of breast cancer development A 20-year prospective study of plasma prolactin as a risk marker of breast cancer development Cancer Res. This evidence concerns the gene PRL and breast cancer.