[Echo-guided transrectal biopsy. An analysis of the results in a series of 1900 patients].

OBJECTIVE

To compare the results of US-guided transrectal biopsy in 1,900 patients with the diagnostic yield of DRE, transrectal US, PSA, PSA density and free PSA/total PSA ratio and to describe our approach based on the results of the comparative study.

METHODS

Over the last two years 1,900 patients have undergone biopsy; 4 to 6 specimens were obtained randomly from both prostatic lobes and areas identified by transrectal US and/or DRE as being suspicious. All patients underwent transrectal US, DRE and determination of serum total PSA and PSA density. Free PSA and free PSA/total PSA ratio were determined in 128 patients with PSA 4-10 ng/ml. Seventy had a second biopsy, 8 a third and 3 had a fourth biopsy.

RESULTS

The overall diagnostic yield was 40%. Biopsy was positive in 27% of patients with PSA 4-10 ng/ml; of these, 64% showed a positive DRE, 21% showed a negative DRE and 13% were negative for both DRE and transrectal US. DRE was positive in 32% of patients with PSA greater than 10 ng/ml, 39% of those with PSA 10-20 ng/ml and 62% of those with PSA greater than 20 ng/ml; transrectal US was positive in 58% of patients with PSA 10-20 ng/ml and in 77% of those with PSA greater than 20 ng/ml. A high specificity was found for both DRE and transrectal US. In patients with PSA 4-10 ng/ml, PSA density at a cutoff of 0.15 ng/ml/cc showed a sensitivity of 81% and a specificity of 20%, respectively. A second biopsy was positive in 20% of patients with a persistently elevated PSA and the incidence of tumors theoretically of little importance was 13%.

CONCLUSIONS

Patients aged less than 70 years whose general condition permit aggressive treatment of prostate cancer should undergo US-guided transrectal biopsy if PSA is greater than 4 ng/ml, regardless of DRE and ultrasound findings. PSA less than 20 ng/ml, PSA density and free PSA/total PSA ratio must be considered for a second biopsy. Sextant biopsy appears to have a good diagnostic accuracy and does not require taking additional specimens or including the transitional zone in the first biopsy. Before classifying a tumor as being of little importance on the basis of the biopsy findings, another biopsy must be performed.