Correlation between F/T-Psa and Echographically-Assessed Prostate Weight in the Diagnosis of Prostatic Cancer

Abstract

The aim of this study was to check whether the combination of clinical-laboratory parameters enables better identification of patients with probable prostate cancer who should undergo echo-guided biopsy, thereby reducing the number of biopsies carried out.

Patients and methods

100 consecutive patients were recruited (mean age 68.2 ± SD 6.7) all with high PSA (mean: 9.3 ± SD 4.3 ng/ml), plus positive TR ultrasound in 85 patients and positive ER in 41 patients referred to our centre for echo-guided prostatic biopsy. Before the biopsy, all patients were sampled to asses the F/T-PSA value with the Immunolite method. Each patient underwent 6–8 echo-guided transrectal biopsies using the Tru-cut 18 G automatic gun. Prostatic weight was calculated echographically (A x B x C x 0.5236). In all, 122 biopsies were carried out in these 100 patients (mean: 1.22 ± SD 0.56). Data was statistically assessed with multiple and logistic regression with variables: age, T-PSA, F-PSA, F/T-PSA, ECT, ER, prostatic weight, number of biopsies per patient. From this analysis, F/T-PSA and prostatic weight proved to be correlated: further multiple regression analysis was carried out on these parameters.

Results

40 cases of prostate cancer were identified and 60 cases of BHP. The regression between the variable that depends on the histological result and the independent variables of F/T-PSA and prostatic weight was extremely significant (p < 0.001). In the light of the results, the following formula was worked out y = 1.077 - (0.025 x F/T - PSA) - (0.008 x prostatic weight). This formula has produced results between 0.04 and 0.9. With a cut-off value of 0.4, 33 prostate cancers were recognised out of 40 and 47 BHP out of 60. Sensitivity was 83%, specificity 78% and efficiency 80%.

Conclusions

F/T-PSA assessment and echographically determined prostatic weight enables a sufficiently sensitive identification to be made of prostate cancer patients who should definitely undergo a biopsy. It is also possible to select those who should be subject to strict follow-up, with consequent reduction (approx 50%) in the number of potential biopsies.