Methylation-specific PCR for DNA-based detection of occult tumor cells in lymph nodes of prostate cancer patients.
OBJECTIVE
To assess the feasibility of methylation-specific PCR (MSP) for the detection of promoter hypermethylation of the detoxifying glutathione-S-transferase P1 gene (GSTP1) to detect occult prostate cancer cells in lymph nodes (LNs).


METHODS
Paraffin-embedded pelvic LNs from 20 patients with pT2pN0M0R0 prostate cancer who developed PSA relapse were assessed by MSP. In 18 of the patients, samples of the primary tumor were obtained for MSP. In 19 patients, bone marrow (BM) aspirates were analyzed preoperatively for disseminated tumor cells by immunocytochemistry (mAb A45-B/B3). In 16 patients, biopsies of the anastomotic region were performed following PSA relapse. As a negative control GSTP1 methylation status was also assessed in LNs from 9 patients for whom an autopsy was performed for non-cancer-related causes.


RESULTS
All primary tumors displayed GSTP1 hypermethylation (HM). Preoperative BM assessment showed disseminated tumor cells in 8/20 cases (40%). In 4 patients, biopsies of the vesico-urethral anastomosis showed local tumor recurrence. The LNs in the cancer patients showed GSTP1 HM in 18/20 cases (90%) versus 1/9 patients (11.1%) in the non-cancer cohort (p<0.0001).


CONCLUSIONS
GSTP1 HM appears to be well suited for molecular staging of prostate cancer and accurately detects disseminated tumor cells in LNs, which was seen in 90% of the patients with PSA relapse. However, the limited number of patients and the finding of benign and malignant prostatic tissue at the vesico-urethral anastomosis as a putative local source of PSA recurrence does not allow us to draw conclusions on the prognostic significance of our findings, yet.
Köllermann
Jens
J
Department of Urology, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Hindenburgdamm 30, 12200 Berlin, Germany. j.koellermann@t-online.de
Müller
Markus
M
Goessl
Carsten
C
Krause
Hans
H
Helpap
Burkhard
B
Pantel
Klaus
K
Miller
Kurt
K
D000368:Aged; D016022:Case-Control Studies; D019175:DNA Methylation; D005260:Female; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction / Q000379:methods*; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000235:genetics / Q000473:pathology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D005982:Glutathione Transferase; D017430:Prostate-Specific Antigen