Significance of prostate cancer missed on needle biopsy tools for retrieving missed cancer

Prostate needle biopsy (PNB) is required for the diagnosis of prostate cancer (PCa), but little is known about the frequency and clinical implication of false-negative results.

To investigate the incidence and clinical impact of minute PCa missed on routine haematoxylin and eosin (H&E) slides, but retrieved by α-methylacyl-CoA-racemase (AMACR) immunohistochemistry.

AMACR immunohistochemistry was used to detect PCa missed on H&E slides in a series of consecutive 1,672 PNB including 1,003 patients without evidence of PCa, and 669 patients with PCa meeting pathological criteria for active surveillance (PCAS) under current clinical investigation, including Gleason score ≤7 (3 + 4), <33% of biopsies involved by cancer, <50% of any core involved by cancer. Using improved multicore (pre-) embedding techniques a single AMACR immunostain/patient was sufficient to detect missed lesions.

In patients without histological evidence of PCa, AMACR immunohistochemistry retrieved minute PCa in 33 of 1,003 patients (3.29%) and atypical small acinar proliferations (ASAP) in 17 of 1,003 patients (1.69%). Among 116 of 669 (17.34%) PCa patients meeting PCAS, detection of additional core(s) involved by cancer was found responsible for disease reclassification in 63 of 116 of patients (54.31%). Limitations include the single-institutional design of the study.

PCa missed on routine H&E histology was retrieved by AMACR in 8.91% of PNB, including 17.34% of PCa patients meeting PCAS. 54.31% of them have finally lost their eligibility for active surveillance after detecting additional cores involved by cancer. Underdiagnosis of limited adenocarcinoma on PNB is a matter of concern, but can be prevented by a single AMACR immunostain/patient if improved multicore (pre-) embedding techniques are used.