KLK3 and prostate cancer: These findings are in agreement with the only other published prospective investigation [2], which found an inverse association between circulating MSP concentration and prostate cancer; in the MEC study, MSP concentration was inversely associated with prostate cancer risk before and after adjustment for PSA, though the association was much stronger after adjustment, as is to be expected due to the strong positive association of PSA concentration with risk and the moderate positive association of PSA with MSP.