Analysis of tumor spillage during radical prostatectomy using RT-PCR of prostate specific antigen

Recent reports have suggested the shedding of cancer cells during radical extirpation of tumors. Prostate cells can be expressed from the prostate ex vivo and found in the expressed prostatic secretions. We conducted an in vivo study to determine if prostate epithelial cells can be found in the operative site as determined by RT-PCR targeted at prostate specific antigen (PSA) and to correlate this with pathologic stage and outcome. We analyzed 14 consecutive radical retropubic prostatectomy procedures with a minimum 1-year follow-up. Intraoperatively, 5-10 ml of fluid (representing blood, urine, and irrigant) was aspirated from the operative field at three time points: after transaction of the dorsal vein complex, urethra, and bladder neck. Ficoll gradient fractionation was carried out on the specimens, and RNA was extracted from the cell pellet. Quality of RNA and presence of the PSA mRNA was determined by RT-PCR targeted at actin and PSA, respectively, using previously published primers. The medical records were reviewed for pathologic stage. There were nine patients with extraprostatic disease and five patients with organ confined disease. Five of 14 (36%) patients tested positive for prostate epithelial cells in the operative field at one or more points during radical prostatectomy. All five positive RT-PCR PSA assays were in patients with locally advanced disease, whereas all of the patients with organ-confined disease were negative for RT-PCR. This preliminary in vivo study suggests that locally advanced prostate cancer may be associated with PSA expressing cells in the operative field during radical prostatectomy. The clinical significance of this is unclear, but this finding suggests that shedding of cells in the operative field is more likely with locally advanced disease.