[The role of prostate volume in ultrasound guided transrectal prostate biopsy: is it as important as a marker as PSA?].

Objectives: The limitations of PSA to identify patients with prostate cancer prompted the definition of different parameters trying to increase specificity without reducing sensitivity. This paper studies the relationship of volume and presence of prostate cancer in sextant biopsies.

Methods: We collected the results of prostate biopsies performed to 6000 patients between 1994 and 2002. 861 of them underwent more than one biopsy, adding up for a total of 7127 biopsies. Various predictive models to identify factors related to positive biopsy were constructed.

Results: Mean prostate volume is 14.6 +/- 66.2 cc for the first biopsy, increasing in successive biopsies to 85.17 cc. A high incidence of prostate cancer was observed in small prostates, reaching 67.2% of those with normal size (< 20 cc) and diminishing with the increase of volume down to only 19.7% in those larger than 50 cc (p < 0.0001). In second biopsies of patients with PSA between 4 and 10 ng/ml and gland volume higher than 50 cc percentage of biopsies positive for cancer was below 10%. Multivariant logistic regression showed that PSA, volume and PSA density were related with positive biopsies, but not free/total PSA ratio.

Conclusions: Standard PSA cutoffs are not adequate for a proper diagnosis of prostate cancer by ultrasound guided transrectal biopsy Volume (BPH) has a significant influence in PSA values and results of the biopsy, so that it should be taken into consideration when indicating biopsies.