Purpose: Although the sextant biopsy technique has been widely used, concern has arisen that this method may not include an adequate sampling of the prostate, especially for large prostate volumes. We conducted a multicenter study in patients with PSA levels <10 ng/ml to determine the influence of the total and transition zone (TZ) volumes of the prostate for predicting whether one single set of biopsies was sufficient to rule out prostate cancer (PCa). These parameters were evaluated in patients in whom PCa was found after one set of systematic sextant biopsies and those in whom PCa was found after a repeat biopsy.
Materials and methods: A total of 1,018 patients were included in this study. All underwent transrectal ultrasound-guided needle sextant and two TZ biopsies of the prostate. Total and TZ volumes of the prostate were measured (prolate ellipsoid method). From this cohort, all patients in whom a benign disease was found after the first set of biopsies underwent a second similar set of biopsies within 6 weeks. Only patients with PCa were included in this study, whether diagnosed on first or repeat biopsy. Uni- and multivariate statistical analysis using the SAS system (Cary, N.C., USA) and ROC curves were used to compare patients in whom the diagnosis was performed after the first set of biopsies and those who required a second set.
Results: Of the 1,018 patients, 344 (33.8%) had PCa diagnosed, 285 (28%) after the first set of biopsies, and 59 (8.1%) on repeat biopsy. As compared to patients diagnosed with PCa after the first set of biopsies, patients diagnosed after the second set had larger total prostate and TZ volumes (43.1+/-13.0 vs. 32.5+/-10.6 cm(3), p<0.0001 and 20.5+/-8.3 vs. 12.8+/-6.0 cm(3), p<0.0001). ROC curves showed that total and TZ volumes of 45 and 22. 5 cm(3), respectively, provided the best combination of sensitivity and specificity for discriminating between patients diagnosed with PCa after the first from those diagnosed after a second set.
Conclusion: In patients with total prostate volume >45 cm(3) and TZ >22.5 cm(3), a single set of sextant biopsies may not be sufficient to rule out PCa. In these patients, a repeat biopsy should be considered in case of a negative first biopsy.