IgGs reactive to prostate-related antigens were also detected in healthy donors and prostate cancer patients (Harada et al, 2003a; Kobayashi et al, 2003; Matsueda et al, 2004) Therefore, we attempted to determine whether IgG reactive to four PTHrP-derived peptides could be detected in the plasma of cancer patients and healthy donors. Here, PTHLH is linked to prostate cancer.