Kinetic analysis of prostatic volume and prostate specific antigen (PSA) in patients with advanced prostatic cancer treated by castration.

The clinical usefulness of the kinetic analysis of prostate specific antigen (PSA) in patients with advanced prostatic cancer treated by castration has not yet been evaluated. The reduction of both prostatic volume and PSA was monitored in 37 patients with Stage C and Stage D prostatic cancer. The change of prostatic volume was measured frequently by transrectal ultrasonography (TRS) after castration, as was the change of PSA. A kinetic analysis of both prostatic volume and PSA was made by comparing the reduction time tau(PSA) (speed of the reduction of PSA) and tau prostatic volume (PV). There was a statistically significant correlation between tau(PSA) and tau(PV) in patients with a tau(PV) of less than 30 days. However, no correlation was observed in patients with a tau(PV) of more than 30 days, because the tau(PSA) in this group fell into a relatively low range similar to the group with a tau(PV) of less than 30 days. It was assumed that the change of PSA after castration reflected mainly the response of the hormone dependent portion of the total cancer volume. However, all data of tau(PV) with a tau(PSA) less than 10 days were within 30 days. In conclusion, tau(PSA) might be promising as a prognostic factor after castration in patient with advanced prostatic cancer, although tau(PSA) was not a direct substitute for tau(PV).