Effectiveness of two ultrasound-guided transrectal biopsy schemes in the diagnosis of prostate cancer. A randomized study.

Objective: To determine whether a 10-core prostate biopsy scheme is superior to the sextant scheme in diagnosing prostate cancer in patients programmed for a first biopsy, with negative rectal digital examination and PSA between 3.5-20 ng/ml.

Methods: A randomized prospective study was performed comparing two prostate biopsy schemes, with randomization stratification according to prostate volume (< or = 50 ml and > 50 ml). Sample size predetermination yielded a minimum of 304 patients in order to achieve the primary objective. Statistical analysis was carried out on an intent-to-treat basis, using the chi-squared test and uni- and multivariate analysis via logistic regression.

Results: Cancer was detected in 27.3% of the cases. A significant association was observed between cancer diagnosis and age (p=0.03), prostate volume (p=0.0001) and ultrasound nodule identification (p=0.0001). No correlation was observed with the total number of cores in the series (p=0.37) or with prostate volume < or = 50 ml (p=0.87) or > 50 ml (p=0.09). In the multivariate analysis, age > 70 years (p=0.005), prostate volume < or = 50 ml (p=0.001), and ultrasound nodule identification (p=0.003) were identified as independent variables associated to cancer diagnosis.

Conclusion: No statistically significant differences were found between the two prostate biopsy schemes. In glands over 50 ml in size, the sextant scheme may prove to be insufficient.