Significance of small foci of Gleason score 7 or greater prostate cancer on needle biopsy.

OBJECTIVES

With increased screening for prostate cancer, we have noted a greater number of patients with small foci of Gleason score 7 or greater prostate cancer on needle biopsy. The significance of these findings is unknown.

METHODS

We studied 57 men with small foci of Gleason score 7 or greater on needle biopsy. Tumor length was less than 1.5 mm in all but 2 cases. In those 2 cases, there were two minute (less than 0.5 mm) foci of cancer separated by 1.8 mm. The length of cancer ranged from 0.2 to 1.8 mm (mean 0.63 mm). In all cases, only one core was involved.

RESULTS

Thirty-three men underwent radical prostatectomy (RP), 14 received radiation, 8 underwent surveillance, and 2 received hormonal therapy. Men who underwent RP were younger (62 years) than those who had radiotherapy (69.1 years), who were younger than those who underwent surveillance (74.5 years). The mean prostate-specific antigen (PSA) for men undergoing RP was 8.0 ng/mL (range 1.4 to 22). Preoperative serum PSA values did not predict organ-confined status. Needle biopsy grades were as follows: 3 + 4 = 7 (n = 30); 4 + 3 = 7 (n = 17); 4 + 4 = 8 (n = 7); 5 + 4 = 9 (n = 1); and 5 + 5 = 10 (n = 2). We were able to review slides in 27 of the RP specimens, of which 24 were well sampled. Of these 24 cases, 33% had positive margins and 33% were not organ confined; the median tumor volume was 0.5 cc (mean 1.04). No difference in RP tumor volume was found between tumors with needle biopsy Gleason primary grade 3 and those with 4 or greater. The percentage of Gleason pattern 4 on needle biopsy weakly correlated with the percentage of Gleason pattern 4 in the RP specimen (P = 0.04). However, the percentage of Gleason pattern 4 only in the RP specimen, but not in the biopsy, correlated with whether the tumor was organ confined.

CONCLUSIONS

The likelihood of having organ-confined disease with small foci of Gleason score 7 or greater on needle biopsy appears to be equivalent to that calculated from the Partin Tables for greater amounts of Gleason score 6 cancer on needle biopsy. In men who are considering RP, small foci of Gleason score 7 or greater adenocarcinoma on needle biopsy should not necessarily be considered an adverse finding.