Abstract: PD65-10
Sources of Funding: Prostate Cancer UK_x000D_ European Urological Scholarship Programme

Introduction

Prostate cancer is a heterogeneous disease both in terms of clinical presentation and pathology which can lead to very different clinical outcomes. Conventional prognostic factors, including serum PSA levels, Gleason score and pathological stage are often inaccurate and histological biomarkers could be useful in distinguishing indolent from aggressive prostate cancers. Tissue microarrays (TMAs) are useful for validating protein biomarker expression in large cohorts of patient samples using immunohistochemistry (IHC) but are often created from radical prostatectomy specimens which do not accurately represent diagnostic biopsies. The limited tumour availability in biopsy samples has led us to develop an improved method for constructing TMAs to study multiple biomarkers simultaneously on biopsy tissues. Objectives: Validate a new method of constructing TMA blocks from prostate needle biopsies and study the link between well known biomarkers (PSA, PSMA, p63,MSMB and AMACR) and mp-MRI data_x000D_

Methods

Patients attending UCLH with suspected prostate cancer were recruited to the PICTURE study and underwent a diagnostic mp-MRI scan and subsequent image-guided biopsy. This was analysed by a pathologist to confirm tumour Grade. Clinical and MRI data were routinely collected. We extracted the regions of tumour within biopsy samples and re-embedded them so that they could easily be repositioned into a recipient TMA block. Blocks were sectioned and stained using automated IHC for established prostate cancer biomarkers including p63, AMACR, PSMA, MSMB and PSA.

Results

We have successfully produced TMA blocks containing representative regions of benign and tumour samples for 200 patients. 99.4% of the cores included were recovered in the TMAs slides. Biomarker expression correlates with Grade of cancer for PSA (p=0.01), MSMB (p=0.016) p63 (p<0.0001), AMACR (p<0.0001) and PSMA (p<0.0001). Expression also correlates with Likert score for PSMA (p=0.009), p63 (p=0.023) and AMACR (p<0.0001).

Conclusions

This new method of constructing TMA blocks is effective at utilising interesting regions of biopsy tissue. It allows multiple biomarkers to be assessed quickly from large cohort studies that accurately represent the tissue routinely used for diagnosis.

Funding

Prostate Cancer UK_x000D_ European Urological Scholarship Programme