Prognostic Impact of RT-PCR-Based Detection of Peritoneal Micrometastases in Patients with Pancreatic Cancer Undergoing Curative Resection

Positive peritoneal fluid cytology predicts poor outcome in patients with resected pancreatic cancer. Reverse transcription-polymerase chain reaction (RT-PCR) has been proposed as a more sensitive means of detection of peritoneal micrometastases than conventional cytology. The clinical significance of RT-PCR positivity in the absence of other evidence of peritoneal disease is unknown. The purpose of the current study was to determine the outcome RT-PCR positive/cytology-negative patients who underwent potentially curative resection. Peritoneal washings were collected prospectively from 115 patients with pancreatic cancer undergoing diagnostic laparoscopy at a single institution. Specimens were analyzed by a cytopathologist and by RT-PCR for carcinoembryonic antigen (CEA). Of the 115 patients, 62 (54%) underwent R0 resection. Eleven of the 62 patients (18%) had peritoneal washings that were negative by conventional cytology but positive for CEA by RT-PCR. Those 11 patients experienced early peritoneal and overall disease recurrence versus those who were RT-PCR negative (P = 0.001, P = 0.003, respectively) independent of nodal status. RT-PCR for CEA is a sensitive and specific method for the detection of clinically significant peritoneal micrometastases from pancreatic cancer and it might identify a subgroup of patients with otherwise negative findings at staging laparoscopy who might respond better to treatment other than primary surgical resection.