[Does the proportion of tumor tissue in biopsies reflect the extent of localized prostate cancer?].

Objectives: To evaluate whether the percentage of biopsy tissue invaded by tumour provides any supplementary information to laboratory and/or biopsy data (Gleason, number...) in the preoperative staging of patients with localized prostatic cancer (T1-T2).

Materials And Methods: 170 patients with a mean age of 65.05 +/- 6.12 years and a mean PSA of 22.5 +/- 21.4 ng/mL were submitted to radical prostatectomy (RP) for T1-T2 prostatic cancer. 110 patients were submitted to a series of 6 transrectal prostatic biopsies to establish the diagnosis. We evaluated the percentage of biopsy tissue invaded. This parameter, as well as the Gleason score and the preoperative PSA, were studied in comparison with pathological criteria of the operative specimen (capsule status, resection margins) and postoperative PSA.

Results: The cut-off value of 10% of invaded biopsy tissue was calculated as being the most discriminant for the prediction of resection margins, capsule status and progression of laboratory parameters. When less than 10% of biopsy tissue was invaded, there were 31.2% positive margins (RM+). 28% of invaded capsules (pT3), and 21.7% of laboratory progression (P+) versus 44.1%, 71.4% and 47%, respectively, when more than 10% of tissue was invaded. The Gleason score of the biopsy did not improve this prognostic evaluation. The mean quantities of invaded biopsy tissue were statistically different between pT3 and pT2, RM+ and RM-and P+ and P-. When only one positive biopsy was invaded by less than 10%, 87.5% of these operated patients remained stable, RM- and pT2.

Conclusions: On an individual level, the percentage of invaded tissue does not reflect the degree of extension or progression of localized prostatic cancer. Only a single positive biopsy invaded over less than 10% of its length is statistically correlated with a good prognosis.