Rapid detection of mutated E-cadherin in peritoneal lavage specimens from patients with diffuse-type gastric carcinoma

Tumor cells in abdominal lavage specimens from patients with gastric carcin oma strongly predict subsequent peritoneal metastasis and poor prognosis. R everse transcription (RT)polymerase chain reaction (PCR) detection of wild- type E-cadherin has been claimed to be superior to conventional cytology fo r the detection of patients who subsequently develop peritoneal metastases. The present study tested this hypothesis and determined whether or not the detection of mutated, tumor-specific E-cadherin messenger RNA in abdominal lavage specimens serve as a useful diagnostic tool. Preoperative lavage sp ecimens from 52 patients with diffuse-type gastric carcinoma and from 5 pat ients with benign disease were analyzed by conventional cytology and by RT- PCR for amplification of E-cadherin. Tumor cells were detected by cytology in 8 (15.3%) of the 52 patients with gastric cancer. The E-cadherin was det ected in all 57 samples by RT-PCR. Two of these had abnormal E-cadherin amp lification products confirmed to be mutations by direct sequencing, which w ere identical in the primary tumors. These findings suggest that the detect ion of wild-type E-cadherin is not sufficiently tumor specific. Also, for d iffuse gastric carcinomas with confirmed E-cadherin mutations, detection of mutant E-cadherin by RT-PCR is a potentially valuable method for tumor cel l detection in lavage specimens.