SHORT-TERM EFFECT OF DIGITAL RECTAL EXAMINATION ON SERUM PROSTATE-SPECIFIC ANTIGEN LEVELS - A PROSPECTIVE-STUDY

Objective: Prostate-specific antigen (PSA) is widely used as a tumor m arker in the early detection of prostate cancer. However, its value is limited by several factors such as not being specific for the cancer tissue, diurnal variations of the secretion, and changes in the serum levels observed following rectal manipulations. The effect of digital rectal examination (DRE) on serum PSA levels is still debatable. Metho ds: A prospective study is conducted by utilizing the IRMA count (mono clonal) PSA assay in order to determine the effect of DRE on PSA serum levels. A total of 50 men (median age 61, range 42-75 years) who pres ented to our outpatient clinic for the first time with lower urinary t ract outflow obstruction symptoms were included in this study. Further evaluation revealed prostate cancer in 5 patients(10%) and benign pro state hyperplasia in the others. Blood samples were drawn for a PSA as say from all patients prior to and 30 min and 24 h following DRE (PSA 1-3). Results: The mean PSA values prior to and 30 min and 24 h follow ing DRE were 4.09 +/- 0.67 range 0.2-19.47) ng/ml, 4.50 +/- 0.63 (0.15 -17.75), and 4.28 +/- 0.68 (0.23-24.12) ng/ml, respectively. The media n PSA levels for PSA 1, PSA 2, and PSA 3 were 2.49 +/- 4.74, 3.22 +/- 4.48, and 2.62 +/- 4.82 ng/ml, respectively. Although, there was a sta tistically significant increase in serum PSA levels 30 min after DRE, the clinical significance of this increase in PSA values with a mean d ifference of 0.4 ng/ml remains to be clarified. Conclusion: Although t he effect of DRE on PSA levels does not appear to be clinically signif icant, in order to prevent any confusion, it may be the best approach to perform DRE after obtaining serum for PSA analysis.