[Genetic diagnosis of pelvic lymph node metastasis using fine needle aspiration samples in prostate cancer]

We have developed a highly sensitive method to detect pelvic lymph node metastasis using the 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 24 patients with prostate cancer. Each aspirated sample (0.05-0.1 ml) was divided into 2 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. The PSA gene was detected by RT-PCR in 11 FNAB samples which included not only all 6 cytologically positive and 2 cytologically class III cases but also 3 of 16 cytologically negative cases. The PSA gene was not detected by RT-PCR of FNAB samples in any of the 20 cases of bladder cancer. Thus RT-PCR for detection of the PSA gene in FNAB samples may be useful as a new diagnostic technique for detection of early lymph node metastasis in prostate cancer and an additional tool for cytological diagnosis of prostate cancer.