18 studies investigated the association between tissue expression of IGF-I (n = 5), IGF-II (n = 4), IGF-IR (n = 7), IGFBP-2 (n = 7), IGFBP-3 (n = 6) with risk of prostate cancer or prostate cancer outcomes such as Gleason Grade or TNM stage. This evidence concerns the gene IGF1 and prostate cancer.