THE EFFECT OF PROSTATE VOLUME ON THE YIELD OF NEEDLE-BIOPSY

Purpose: Early diagnosis of prostate carcinoma has undergone significa nt evolution mainly due to the widespread use of serum prostate specif ic antigen, transrectal ultrasonography and spring loaded biopsy devic es. A common dilemma faced by clinicians arises when a negative biopsy is obtained in a patient and there is a high suspicion for prostate c arcinoma. The literature reveals a 20 to 40% positive repeat biopsy ra te in men with elevated prostate specific antigen who had an initial n egative biopsy.(1-3) We determined the yield of 6 systematic sector bi opsies as a function of total gland and peripheral zone volumes.Materi als and Methods: The database of transrectal ultrasound guided prostat e needle biopsies performed at the Department of Urology, University o f Washington Medical Center and Veterans Affairs Puget Sound Health Ca re System was reviewed. The yield of the 6 biopsies was determined as a function of the total gland and peripheral zone volumes. Results: A total of 1,057 men who underwent transrectal ultrasound guided prostat e needle biopsies were investigated in our study. Of the men 326 were diagnosed with prostate cancer for a positive biopsy rate of 30.8%. No relationship between gland size and cancer yield was seen using total gland volume compared to the first quartile until the largest quartil e when a significantly lower cancer detection rate was noted (odds rat io 1.5). Conclusions: The positive yield of the systematic 6-sector bi opsy decreases significantly when the total gland volume is greater th an 55.6 cc or peripheral zone volume is greater than 33.61 cc. In men with smaller prostates 6 systematic sector biopsies should be adequate .