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

We have developed a highly sensitive method to detect pelvic lymph node(LN) metastasis using reverse transcriptase-polymerase chain reaction(RT-PCR) with the primers specific for prostate-specific antigen(PSA) gene in combination with the fine needle aspiration biopsy(FNAB). The specimens were obtained from pelvic LN from 15 prostate cancer patients and 15 bladder cancer patients. The aspirated samples (0.05 approximately 0.1 ml) were used for detecting the fragment of PSA mRNA by RT-PCR and Southern blot analysis, and the rest of samples were submitted to conventional cytology. Expression of PSA gene was detected in 9 cases of FNAB samples including all 5 cytologically positive and further more 2 cytologically class III cases, and 2 of 8 cytologically negative cases. RT-PCR of FNAB samples from all cases of bladder cancer were negative for the detection of PSA gene. The sensitivity of PSA gene by RT-PCR was very high and could detect 10 degrees cancer cell. In conclusion, our study suggested that RT-PCR for detection of PSA gene in FNAB samples might become a new diagnostic tool for detection of small foci of prostatic cancer metastasis in LN and combination use of RT-PCR and cytology could greatly contribute to accuracy in diagnosis.