The significance of prior benign needle biopsies in men subsequently diagnosed with prostate cancer

Purpose: We determine the relationship between a history of benign needle biopsies, and the volume and location of cancer. Materials and Methods: We evaluated 395 men who underwent radical prostatectomy for stage T1c (nonpalpable) prostate cancer. Results: Of the men 74 had 1 or more prior benign needle biopsies. Prior benign biopsy correlated with tumor in the anterior or lateral portion of the radical prostatectomy specimen (p = 0.044) and prostate weight (p = 0.002). The likelihood of prior benign biopsy was 32.5% for men with a 75 gm. or greater prostate compared to 15.2% for those with a less than 75 gm. prostate. Although prior benign biopsy correlated with 'very limited' tumor in the prostate (less than 0.2 cc, no Gleason pattern 4 or 5 and organ confined disease) (p = 0.005), only 28.4% of patients with prior benign biopsy had 'very limited' tumor. In a multivariate analysis prior benign biopsy correlated only with anterior or lateral distribution and enlarged prostate size. Of the prior benign biopsy cases 12% had positive margins, average tumor volume was 1.15 cc and 27% had nonorgan confined disease. These figures were not different from those in cases with cancer on the first biopsy. In prior benign biopsy cases although PSA velocity predicted tumor volume and 'very limited' tumor, a specific clinically useful cutoff value was not present. Needle biopsy grade and number of positive cores were not predictive of tumor volume or 'very limited' cancer. Conclusions: Prior benign biopsy in men subsequently diagnosed with prostate cancer does not indicate indolent tumor. Benign biopsies are more likely in larger prostate glands and when cancer is in the anterior and lateral regions of the gland, suggesting the need for different biopsy strategies to improve cancer detection.