Detection of disseminated cancer cells in linitis plastica-type gastric carcinoma

Dissemination of cancer cells in the abdominal cavity may lead to peritoneal carcinomatosis, a common event in the linitis plastica type of gastric carcinoma. Reverse transcriptase polymerase chain reaction (RT-PCR) is a sensitive technique for detecting these cells.

Peritoneal washings were obtained during laparotomy from 47 consecutive linitis plastica patients who preoperatively were considered candidates for curative resection. Together with conventional cytological examination using Papanicolaou staining, real-time RT-PCR was performed to quantitate prospectively carcinoembryonic antigen (CEA) mRNA in these washings. Samples above a cutoff value for CEA mRNA were considered positive for molecular detection of disseminated cancer cells.

Conventional cytological examination was positive in 43% (20/47). Positivity of CEA mRNA was much higher at 83% (39/47) and peritoneal carcinomatosis actually was observed in 77% (36/47), either at laparotomy or during postoperative follow-up. Although only two of eight patients who were negative for CEA mRNA suffered from peritoneal carcinomatosis, three more patients died of recurrences through other metastatic pathways. Multivariate analysis revealed that curability of the operation (knowledge of the CEA mRNA values excluded) and T categories were the only significant independent prognostic factors.

RT-PCR of the peritoneal washes had little value as a prognostic factor, but identified over 80% of the patients planned for curative surgery to have disseminated cancer cells in the peritoneal cavity. Almost the same proportion of patients actually suffered from peritoneal carcinomatosis. These facts indicate why treatment with surgery alone rarely cures patients with linitis plastica.