Obtaining fresh prostate cancer tissue for research: A novel biopsy needle and sampling technique for radical prostatectomy specimens

Abstract

Fresh or fresh-frozen tissue samples are preferred for molecular profiling as formalin fixation degrades intracellular nucleic acids. Radical prostatectomy (RP) specimens are a valuable source of prostate cancer tissue, but the reliance on whole-organ pathological processing for prognostication limits sampling opportunities. Few studies have addressed specific harvesting techniques using prostatectomy specimens. Ex vivo biopsies were performed on 23 consecutive fresh RP specimens using a purpose-designed needle. A standard sextant approach was used with an additional lateral biopsy on each side. Cores from each lobe were snap-frozen together and sections assessed by a pathologist blinded to the RP and pre-operative biopsy pathology. Comparison with pre-operative biopsies was performed using the t-test and chi(2) statistical tests. Eleven randomly selected RP specimens were further evaluated for the effects of needle tracks and margin perforation. Cancer was detected in 19 of 23 specimens, giving a sensitivity of 83.6%. The average tumor involvement was 28.3% per section compared with 15.6% for pre-operative biopsies (P < 0.02). There was no statistically significant difference between the groups for either Gleason sum score concordance or tumor location concordance. In 3 of 11 cases, needle margin perforation was identified; in none of the cases did it compromise pathological assessment, although in one case a deeper block resection was required. Ex vivo biopsy is a useful technique for retrieving fresh tissue whilst preserving organ morphology in RP specimens. The purpose-designed needle and harvesting technique provide good yields of cancer tissue from a high proportion of sampled prostatectomy specimens.