Molecular Staging of Micrometastasis in Prostatic Cancer using RT-PCR

Kim, Bup Wan; Kwen, Soon Weon; Chang, Sae Kook; Jung, Yoon Bok; Kim, Jung Wan

Abstract

PURPOSE: Despite advances in the treatment of cancer, recurrence and metastasis continue to pose major problems in clinical mamagement. Recently, molecular based peripheral blood assay using the reverse transcriptase-polymerase chain reaction(RT-PCR) has been shown to be highly sensitive molecular staging modality for detecting extraprostatic disease pre-and post-operatively. The assay uses primers those are specific for prostate specific antigen(PSA) and prostate specific membrane antigen(PSMA). MATERIALS AND METHODS: We compared the application of RT-PCR assay for PSA versus PSMA. These assays were applied to ribonucleic acids extracts from the peripheral blood lymphocyte fraction of 29 patients with metastaic prostate cancer, in which, 13 cases were non neoadjuvant hormonal therapy(NHT) group. In addition, blood specimens from 5 clinically localized cancer were tested. RESULTS: Of 13 metastatic untreated patients 6 had positive for PSA, while 10 cases had positive results for PSMA. Among the 16 patients with hormone treated metastatic cancer patients, 8 (50%) had positive for PSMA while only 1 had positive for PSA. Of 5 localized prostatic cancer, only 1 had positive result just for PSMA. In neoadjuvant hormone treated group, marked reduction in incidence of positive RT-PCR for PSA was noted. An additional explanation is that PSMA may be expressed in hormone refractory cancer. CONCLUSIONS: Presently RT-PCR assay using PSMA is highly sensitive and more accurate than PSA RT-PCR for predicting micrometastasis. We are continuing to increase our patient number and may increase our ability to detect early localized cancer using a molecular approach.