Objective: To assess the course of cancer-free survival and thus determine how reliably reverse transcriptase-polymerase chain reaction (RT-PCR) can detect prostate-specific antigen (PSA)-expressing cells, as patients with untreated lymph node-positive prostate cancer tend to have a poor prognosis, whereas those treated with radical prostatectomy (RP) and immediate adjuvant hormonal therapy show excellent local disease control and a disease-free survival comparable with that of patients with negative lymph nodes, but the detection of micrometastatic disease in pelvic lymph nodes remains a major challenge.
Patients and methods: Quantitative RT-PCR was used to detect PSA mRNA expression in total RNA of 457 pelvic lymph nodes from 70 patients who had RP (53 patients) or laparoscopic lymphadenectomy (17) at our clinic in 1999/2000. For this purpose, alternate sections of lymph node tissue were either snap-frozen for later RNA isolation or examined by standard histopathological methods. Clinicopathological data, adjuvant treatments and follow-up data were recorded for all patients.
Results: After January 2006 (6-year observation period), 13 patients had no follow-up data, while 27 had biochemical (PSA) recurrence or other evidence of clinical progression (two died from prostate cancer), and 30 had no signs of recurrence. Compared to the 'reference' standard (histopathology), the PCR method had a sensitivity of 83% and a specificity of 66%. The method had a positive predictive value of 52% and a negative predictive value of 57%.
Conclusion: Considered alone, pelvic lymph node PSA RT-PCR does not predict the clinical course better than a histopathological assessment of lymph nodes. However, it also identifies some patients with negative histology who later show progression. When added to the pathological classification, PSA RT-PCR improves the detection rate of primary lymphatic dissemination.