The effect of digital rectal examination on serum levels of prostate -specific antigen

Kwon, Dong Deug; Ryu, Soo Bang

Abstract

The prostate-specific antigen (PSA) has been considered a useful tumor marker in monitoring responses, disease progression and recurrence after therapy in patients with prostatic cancer. However. The effect of digital rectal examination on serum PSA determination has remained controversial. The author. therefore. investigated the influence of examination on seurm PSA values. Blood samples were taken before (T0) and 5 minutes (T1), 1 hour (T2), 24 hours (Ts) and I week (T4) after digital rectal examination and the concentration of serum PSA was measured using a Tandeme radioimmunometric assay in 49 persons including 7 patients with prostatic cancer. 27 patients with BPH and 15 controls free of prostatic disorder, The following results were obtained. 1. In normal control group. the mean (+/-SD) PSA values before and 5 minutes, 1 hour. 24 hours and l week after digital rectal examination were 1.51+/-1.12, 2.12+/-1.57. 2.53+/-1.62, 2.39+/-1.41 and 1.97+/-1.20 (ng/ml) respectively. Although serum PSA values measured at 5 minutes. 1 hour, 24 hours and 1 week after digital rectal examination were significantly elevated (p<0.05), most of post-examination PSA values remained within the normal range. 2. In benign prostatic hyperplasia. statistically significant differences between PSA values before and 1 hour and 24 hours after digital rectal examination were observed (p<0.05), while in prostatic cancer group. there were no significant differences between paired pre-examination and post-examination mean PSA values. 3. There were statistically significant differences between PSA values before and 5 minutes, 1 hour, 24 hours and 1 week after rectal examination in normal-value group (<4.0 ng/ml) and between PSA values before and 1 hour after rectal examination in high-value group (>4.0 ng /ml). These results suggest that the evaluation of the concentration or PSA level for prostatic cancer suspected should be done before or immediately after prostatic manipulation.