IGF1 and Familial prostate cancer: In men of the HPFS10, 11, 12 and PHS14 cohorts, loss of PTEN was significantly associated with higher IGF1R expression (P = 0.03).34 These findings suggest that high‐grade prostate cancer requires minimal activation by IGF‐1, and that the IGF‐1 threshold level for tumorigenesis might be lower.