IMPLICATIONS OF PROSTATE MICROMETASTASES IN PELVIC LYMPH-NODES - AN ARCHIVAL TISSUE STUDY

Objectives. In the United States, radical retropubic prostatectomy for adenocarcinoma usually includes a staging pelvic lymphadenectomy. If frozen section analysis of the lymph nodes fails to reveal any evidenc e of metastases, the prostate is removed, We have previously noted tha t as many as 56% of patients undergoing radical prostatectomy demonstr ate rising serum prostate-specific antigen (PSA) levels by 4 years pos toperatively. This report was designed to determine whether micrometas tases undetectable by conventional pathologic methods could have accou nted for these biochemical failures. Methods. A retrospective analysis of formalin-fixed paraffin-embedded pelvic lymph node material was un dertaken using a reverse transcription-polymerase chain reaction (RT-P CR)-based assay designed to amplify messenger RNA from PSA. All specim ens were obtained from a group of 57 patients with prostate cancer who had undergone staging pelvic lymphadenectomy at the time of radical p rostatectomy, and whose long-term follow-up was known. Results. Althou gh all of these nodes appeared to be free of tumor by conventional pat hologic methods, a RT-PCR assay was used to identify evidence of prost ate metastases in 44% of evaluable samples. Of these, 14 of 16 went on to manifest rising serum PSA values by 5 years postoperatively. Concl usions. These results suggest that molecular staging of pelvic lymph n odes prior to planned therapy for clinically organ-confined prostate c ancer may better distinguish between patients with local disease and t hose for whom local therapy alone will not be curative, To our knowled ge, this is the first large-scale retrospective gene expression study published.