Detection of cancer in radical prostatectomy specimens with no residual carcinoma in the initial review of slides.

BACKGROUND

Radical prostatectomy (RP) specimens occasionally contain no carcinoma in the initial slides of an entirely submitted specimen, but no protocol has been established to assess for carcinoma in the remainder of the specimen.

DESIGN

We evaluated 34 cases with no carcinoma in the initial slide review of the entirely submitted RP over a 2-year interval out of 2200 RPs. Our sequential protocol for cases with no initial tumor is (1) review the biopsy; (2) do immunostains on suspicious foci; (3) perform levels on blocks with high-grade prostatic intraepithelial neoplasia; (4) perform 3 levels on the posterior sextant and adjacent sextant region where cancer was identified on biopsy; and (5) flip the blocks in these regions and perform 3 additional levels.

RESULTS

The mean age was 58.1 years (41 to 69 y) with a mean prostate-specific antigen level of 5.9 ng/mL (0.8 to 19 ng/mL). On review, all of the biopsies had carcinoma with a Gleason score (GS) of 3+3=6. The number of positive cores was 1 [n=29 (85%)], 2 (n=3), 3 (n=1), and 4 (n=1). Fifty-nine percent (20/34) of the biopsies had immunohistochemistry (IHC) for basal cells and/or alpha-methylacyl CoA racemase. RPs on average weighed 73.6 g (36 to 155 g). Of the 34 cases with no initial cancer, cancer was found in 26 (76%), and 8 (24%) had no residual carcinoma despite extensive leveling in all cases and IHC in 1 case. IHC was performed on 12 of the 34 RP cases. Of 26 RP cases with cancer, 22 had cancer on only 1 slide, and 4 had cancer on 2 slides. All of the cancers in the radical prostatectomies were GS 6, and the GS agreed with the corresponding biopsy in all cases. In 83% (20/24) of cases that specified laterality in the biopsy, RP carcinoma was ipsilateral to carcinoma in the biopsy. In 93% (14/15) of the cases that specified sextant site in the biopsy, the location of the carcinoma in the RP was in the same or the adjacent inferior-superior sextant site. Of the 29 cases that required leveling, in 7 cases cancer was found only after flipping the blocks and doing additional levels. Of the 8 cases with no cancer, all biopsies had only 1 positive core with 6/8 having <10% of the core involved.

CONCLUSIONS

In about 1.5% of RP cases no tumor will be seen in the initially entirely submitted specimen. A methodical limited targeted approach to identifying cancer can identify cancer in 73% of the cases with no initial cancer, yet there will still be 0.4% of all RPs where cancer is not been identified. As cancer was seen in areas away from the biopsy site in some of our cases with minute tumor, leveling all the blocks may have identified cancer in some of the cases in which we found no tumor with our protocol.