Importance of posterolateral needle biopsies in the detection of prostate cancer

Objectives. To determine whether needle biopsy of the posterolateral aspects of the prostate aids in prostate cancer detection. In the routine sextant biopsy strategy, the posterolateral aspects of the prostate are not sampled. Methods. Using an 18-gauge biopsy gun, we performed sextant biopsies and an additional nine needle biopsies in the pathology laboratory on 150 radical prostatectomy specimens performed for Stage T1c prostate cancer. The additional nine biopsies consisted of three midline biopsies and six (three each from the left and right) posterolaterally aimed biopsies from the apex, mid, and base regions of the gland. Significant tumors were defined as those greater than 0.5 cm³, or with a Gleason score of 7 or greater, or non-organ confined. Results. Of the 123 cases with cancer on repeated biopsy, in only 3 (2.4%) was the only cancer found in the midline biopsies. For the following analysis, we analyzed the data as if we had not done the midline biopsies. If one had performed only the routine sextant needle biopsies, in 31 (25.2%) of the 123 cases, tumor would have been missed; 20 of these tumors were significant, including 5 with extraprostatic extension. If one had performed only the more posterolateral six biopsies, in 15 cases (12.2%), tumor would have been missed; 5 of these tumors were significant, all of which were organ confined. Conclusions. Adding routine midline biopsies does not appreciably increase the detection of cancer. If one were to only perform six needle biopsies of the prostate, these biopsies should be aimed more toward the posterolateral aspect of the gland. Maximum cancer detection results from combining both routine sextant and posterolateral needle biopsies.