Prostatic transition zone directed needle biopsies uncommonly sample clinically relevant transition zone tumors.

PURPOSE: We compared prostate cancer detected in transition zone directed needle biopsies with those in corresponding radical prostatectomy specimens.
MATERIALS AND METHODS: We reviewed needle biopsy and radical prostatectomy slides from 61 patients in whom cancer was present on transition zone directed needle biopsy. We assessed needle biopsy cancer features as well as transition zone lesions and dominant tumor sites on radical prostatectomy.
RESULTS: Prostate cancer was detected in 25 of 61 left (41%), 23 of 61 right (38%) and 13 of 61 bilateral (21%) transition zone directed needle biopsies. On radical prostatectomy 24 of 61 cases (39.5%) had no tumor in the transition zone, 24 of 61 (39.5%) had nondominant transition zone cancer and 13 of 61 (21%) had a dominant transition zone lesion. Of cases with cancer in the left and right transition zone directed needle biopsy 18 of 38 (47%) and 17 of 36 (47%), respectively, had no transition zone tumor or showed tumor in the contralateral transition zone only at radical prostatectomy. In 8 cases the transition zone directed core was the only one with cancer on needle biopsy and 2 of 8 (25%) such cases showed dominant transition zone cancer at radical prostatectomy.
CONCLUSIONS: Cancer identified in transition zone directed needle biopsy cores was not from the transition zone or did not reflect a dominant transition zone lesion in almost 80% of cases. Cancer identified in a left or right transition zone directed needle biopsy did not predict ipsilateral transition zone cancer in almost 50% of cases. These findings suggest that such biopsies do not adequately characterize transition zone tumors. Thus, care should be taken in their interpretation.