[Study on micrometastases in pelvic lymph nodes detected by real-time reverse transcriptase polymerase chain reaction with clinically localized prostate cancer before radical prostatectomy].

Objective: To clarify the significance of micrometastases in pelvic lymph nodes in patients with neoadjuvant hormonal therapy (NHT) before radical prostatectomy (RP).
Methods: Twenty-one patients with clinically localized prostate cancer who received NHT between August 2007 and March 2010 were observed. The patients were clarified into four groups: pathological examination was positive (group A), real-time PCR examination targeting prostate specific antigen (PSA) mRNA and prostate specific membrane antigen (PSMA) mRNA were positive (group B), pathological examination and real-time PCR examination targeting PSA mRNA and PSMA mRNA were both negative (group C), and the control group (group D). After a standard bipedal lymphangiography the films were reviewed carefully by an experienced radiologist. If positive lymph nodes were seen or suspected, a thin-walled 22 gauge needle were directed transabdominally under fluoroscopic control into the area of question and an aspirate was obtained. The expression of PSA and PSMA in aspirate were assessed by a fully quantitative real-time PCR. The specimens were regarded in which either PSA mRNA or PSMA mRNA were positive as showing the "presence of micrometastasis". Lymph node specimens were also stained immunohistochemically with an antibody PSA after RP.
Results: Pathological examination detected lymph node metastases from 3 cases, and real-time PCR further identified lymph node micrometastases from 14 cases with no pathological evidence of nodal involvement. The expression level of PSA mRNA and PSMA mRNA were statistically significant in patients with histological confirmed lymph node metastases and micrometastases detected by real-time PCR despite the lack of histological evidence, and the expression level of PSA mRNA and PSMA mRNA in aspirate were higher than the lymph node between the group A and group B.
Conclusions: Although residual foci of atrophic prostate cancer cells in resected lymph nodes after NHT can be difficult to diagnose by pathological examination, the present results show the usefulness of quantitative real-time PCR targeting PSA and PSMA mRNA for detected micrometastatic tumour foci in pelvic lymph nodes from fine needle aspiration biopsy of lymph nodes before RP.