DNA ploidy and PTEN as biomarkers for predicting aggressive disease in prostate cancer patients under active surveillance by Cyll, K, Skaaheim Haug, E, Pradhan, M, Vlatkovic, L, Carlsen, B, Löffeler, S, Kildal, W, Skogstad, K, Hauge Torkelsen, F, Syvertsen, RA, Askautrud, HA, Liestøl, K, Kleppe, A, Danielsen, HE