KLK3 and prostate cancer: Table 4 demonstrates that the overall diagnostic accuracy of PSA declines dramatically from 63% at age 50 to 35% at age 70. It is thus a significantly less effective test for detecting prostate cancer in older patients. This decline in the overall diagnostic accuracy conforms with Equation 12, which predicts a decline in the overall diagnostic accuracy when the sensitivity (21% for PSA) is lower than the specificity (91% for PSA).