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Keywords:

  • vulvar cancer;
  • RT-PCR;
  • carbonic anhydrase-9;
  • lymph node;
  • sentinel lymph node;
  • micrometastasis

Abstract

Regional lymph node status is an important prognostic factor for vulvar cancer. The goal of our study was to elaborate a reliable test for detecting micrometastases, undetectable by traditional methods, in the lymph nodes of vulvar squamous carcinoma patients. For this purpose, carbonic anhydrase-9 (CA9) was investigated as a cancer-related marker by RT-PCR. Firstly, primary carcinoma specimens were examined for CA9 expression by immunohistochemistry with M75 monoclonal antibody. All 19 tissues exhibited a variable degree of staining, which was mostly confined to the plasma membranes of tumor cells. Correspondingly, all primary tumor specimens and the control A-431 vulvar cancer cell line gave a positive signal in the nested RT-PCR assay designed to detect CA9-expressing cells with a high sensitivity. Analysis of 77 lymph node specimens from 20 patients revealed a full correlation between RT-PCR results and standard hematoxylin–eosin staining in 75% of samples, whereas 25% of specimens were negative by the standard method and positive for CA9 mRNA, accounting for 28% of all histologically negative lymph nodes. There were no false-negatives with RT-PCR. A positive inguinal lymph node with a negative sentinel node was observed in the same groin only once in 38 specimens. Our findings clearly indicate potential value of CA9 as a molecular marker for the assessment of regional lymph node status in vulvar cancer patients and support a possible utility of our RT-PCR assay in the detection of micrometastases. © 2005 Wiley-Liss, Inc.