Molecular staging of prostatic cancer with RT-PCR assay for prostate-specific antigen in peripheral blood and lymph nodes: comparison with standard histological staging and immunohistochemical assessment of occult regional lymph node metastases.

Background: About 30-40% of men with localized prostate cancer undergoing radical prostatectomy will have cancer recurrence. It is estimated that one third recur locally and two thirds develop distant metastases with or without local recurrence.

Methods: In the present study we investigate the detection of prostate-specific antigen (PSA) mRNA in peripheral blood samples (n=200 patients) and pelvic lymph nodes (n=154 patients) by PSA reverse transcriptase polymerase chain reaction (RT-PCR) and compare these results to standard histological and immunohistochemical staging.

Results: We have observed a statistically significant correlation of lymph node PSA RT-PCR with standard pathologic risk factors, such as Gleason score (p=0.011), the presence of Gleason patterns 4 or 5 (p=0.005), lymph node metastasis (p<0.001) and a nearly significant correlation with the pT category (p=0.087). 39.5% (57/145) of the pN0 patients had PSA mRNA detectable in their lymph nodes. Blood PSA RT-PCR showed no correlation with the aforementioned factors and was even inversely correlated with preoperative serum PSA and lymph node status. Immunohistochemistry did not detect unsuspected prostate micrometastases in any pN0 patient.

Conclusions: Lymph node PSA RT-PCR correlates with the Gleason score and the presence of Gleason patterns 4 or 5. Further clinical follow-up and correlation of RT-PCR status with overall outcome is required to allow validation of lymph node RT-PCR as a predictor of distant disease recurrence.