Influence of prostate volume in the detection of prostate cancer

Abstract

Objectives To assess the influence of prostate volume on prostate cancer (CaP) detection in men who underwent repeated sextant transrectal ultrasound biopsy of the prostate. Methods Between September 1991 and September 2000, 4376 men underwent sextant transrectal ultrasound-guided biopsy of the prostate. Of the 4376 men, 556 underwent repeat biopsy because of persistent prostate-specific antigen elevation (greater than 4 ng/mL) and/or an abnormal digital rectal examination or suspicious pathologic findings. The percentage of CaP missed on the initial biopsy and detected on the repeat biopsy between arbitrary prostate volumes of less than 50 and 50 cm 3 or greater and between less than 37.5 and 37.5 cm 3 or greater, the median prostate volumes of men with CaP, were compared. Patient age, prostate-specific antigen level, digital rectal examination findings, and Gleason score in each volumetric cutoff group were also compared. Results CaP was detected in 22% of men who underwent a repeat biopsy. The percentage of CaP missed on the initial biopsy but subsequently detected on the repeat biopsy consistently increased as the volume increased. A statistically significant difference in the percentage of CaP not detected on the initial biopsy was found between prostate volumes of less than 50 and 50 cm 3 or greater and between less than 37.5 and 37.5 cm 3 or greater ( P <0.05). No statistically significant difference in prostate-specific antigen, age, digital rectal examination, or Gleason score was found between each volumetric cutoff group. Conclusions A significant percentage of men are diagnosed with CaP after a repeat biopsy. We have demonstrated that the percentage of CaP missed on the initial biopsy and detected on the repeat biopsy increases as the prostate volume increases. The results of our study suggest that in men with large prostates, traditional sextant biopsies may not be adequate to detect CaP.