Detection of prostate specific antigen messenger RNA from pelvic lymph node in prostate cancer

We have adapted a sensitive method to detect pelvic lymph node metastasis using reverse transcriptase-polymerase chain reaction (RT-PCR) with primers specific for prostate-specific antigen (PSA) gene. Fine needle aspiration biopsy (FNAB) of pelvic lymph nodes was performed in 25 patients with prostate cancer. Each aspirated sample (0.05-0.1 mL) was divided into two parts: one for RNA extraction and RT-PCR to detect the fragment of PSA mRNA, and the other to smear on a slide glass for conventional cytology. RT-PCR detection of PSA gene was positive in 12 cases of FNAB samples, which included not only all 6 cytologically positive and 2 cytologically class III cases but also 4 of 17 cytologically negative cases. RT-PCR of FNAB samples of all 20 cases of bladder cancer were negative for the detection of PSA gene. RT-PCR for detection of PSA gene in FNAB samples may become a new diagnostic technique for detection of early lymph node metastasis in prostate cancer and an additional tool for cytologic diagnosis of prostate cancer.