Length of prostate biopsies is not necessarily compromised by pooling multiple cores in one paraffin block: an observational study

Use of Prospective Multiplex Immunohistochemistry to Redefine Tissue Pathways of Diagnostic Core Biopsy of Prostate

The incidence of prostatic cancer in the United Kingdom has increased over 40% in the past 30 years. The majority of these cancers are diagnosed by core biopsy, posing a considerable strain on a service that struggles to recruit sufficient histopathologists. The current methodology for tissue diagnosis has a significant false-negative rate, small false-positive rate, and a proportion of indeterminate diagnoses. Therefore, this area presents an opportunity both to improve diagnostic quality and to reduce the burden on resources. We investigated streamlining tissue pathways by increasing the utilization of readily available resources to reduce the burden on scarce resources and improve the accuracy of diagnosis. This involved applying prospective multiplex immunohistochemistry (IHC) using 4 different markers (CK5, p63, racemase, and Ki-67) and 2 chromogens. We conducted a prospective study using over 8000 cores and 3 consultant histopathologists. The pathologists assessed each core using either conventional stains (hematoxylin and eosin) only or multiplex IHC only. The results of this assessment were later compared with the overall assessment made for the final histologic diagnosis. Results show that IHC alone has a positive predictive value of 98.97% and a negative predictive value of 99.91%, while hematoxylin and eosin alone has a positive predictive value of 94.21% and negative predictive value of 99.07%, demonstrating improved diagnostic accuracy. When assessed against the use of on-demand IHC, prospective IHC improves turn-around-times, reduces indeterminate diagnoses, improves pathologist's accuracy and efficiency and, in overall terms, is cost-effective. In addition, it is possible to structure these tests within the routine of a diagnostic service with little impact on the overall capacity of the laboratory.

The 3DBiopsy Prostate Biopsy System: Preclinical Investigation of a Needle, Actuator, and Specimen Collection Device Allowing Sampling of Individualized Prostate Lengths Between 20 and 60 mm

OBJECTIVE

To increase the likelihood of detecting anterior cancers within the prostate and provide a specimen that spans the length of the gland. Newly designed 17- and 15-gauge (G) biopsy needles, a variable actuator, and an integrated pathology system intended for the longer cores were developed and tested for this purpose.

MATERIALS AND METHODS

Testing was performed comparing 2 common cannula tip grinds, a Vet-point (sharp tip) and a Menghini-point (atraumatic tip), and were tested against 18-G Bard Monopty in porcine kidney. A variable actuator was developed to fire the needle 20-60 mm and tested in cadaver prostates.

RESULTS

The aggregate firings for 3 different shot lengths comparing the Vet- with the Menghini-tip cannulas demonstrated 91% vs 85.2% fill (length of specimen/length of core bed, P = .007). A 15-G trocar needle with the Vet-tip cannula also had the best performance, with an aggregate standard deviation of 6.4% across 3 firing ranges and a minimum to maximum specimen length of 81%-105% of potential fill. Cadaver testing with the Vet-tip needles in the actuator for the transrectal (17-G) and transperineal (15-G) biopsies demonstrated mean fills of 93.3% and 76.5%, respectively. The new transrectal ultrasound needle obtained a 2-fold increase in specimen length over the standard Bard device (P <.001).

CONCLUSION

Longer and consistent cores were obtained using the new biopsy needles. Combined with an adjustable actuator, the physician can obtain specimens that include peripheral and anterior zone tissue in 1 core. Determination of cancer location on the longer specimens could enhance focal therapy planning.

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

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.