Prospective Analysis of Prostate-Specific Markers in Pelvic Lymph Nodes of Patients With High-Risk Prostate Cancer

Abstract

Background: Pathologic evidence of pelvic lymph node involvement is obtained in 12%-20% of patients with localized prostate cancer that exhibits high-risk features (defined on the basis of tumor size, serum prostate-specific antigen [PSA] level, or Gleason score). The rate of systemic failure (i.e., relapse) in patients with this type of prostate cancer and no pathologic evidence of regional lymph node involvement is 55%-92% within 5 years of definitive local therapy. Since reverse transcription-polymerase chain reaction (RT-PCR) methods are likely to be more sensitive than routine pathologic examination in detecting metastatic tumor cells, we compared the ability of the two approaches to detect prostate cells in the pelvic lymph nodes of patients with localized, high-risk disease. Methods: Fifty-eight lymph node specimens isolated from 33 patients before definitive local therapy were examined. Expression of PSA and prostatespecific membrane antigen (PSM) messenger RNAs in the specimens was assessed by means of nested RT-PCR. Results: Pathologic examination identified tumor cells in the lymph nodes of four (12%) of the 33 patients, and PSA and/ or PSM expression was positive in specimens from 27 (82%) of the patients (two-sided P <.0001). The four patients with positive pathologic findings also had positive RT-PCR results. Among the 29 patients with no pathologic evidence of lymph node involvement, 23 (79%) tested positive by means of RT-PCR. In these 23 patients, PSM expression was detected more frequently than PSA expression; however, in two patients, only PSA expression was detected. Conclusions: Expression of prostate-specific markers in the pelvic lymph nodes of patients with localized, high-risk prostate cancer may indicate the presence of metastatic tumor cells. Such cells may be responsible for the high rate of systemic failure seen in these patients. Additional studies are required to determine the prognostic relevance of our findings.