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

Abstract

Background: 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.

Materials and methods: 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.

Results: 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.

Conclusions: 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.