Detection of circulating cancer cells after a gastrectomy for gastric cancer.

Purpose: In this study, we evaluated the correlation between the postoperative detection of circulating cancer cells and the risk of recurrence in patients with gastric cancer.

Methods: Total RNA was extracted from 1.5 ml of peripheral blood from 59 patients with gastric cancer and 15 patients with cholecystolithiasis (control) before and after operation. Carcinoembryonic antigen (CEA) messenger RNA (mRNA) was used as a probe to detect gastric cancer cells in samples using a real-time reverse transcription-polymerase chain reaction (RT-PCR).

Results: Carcinoembryonic antigen mRNA-positive cells were not found in the peripheral blood of the control patients either before or after operation, nor in the peripheral blood of the gastric cancer patients before operation. However, CEA and mRNA-positive cells were detected in 46% of the patients just after a gastrectomy, though these circulating cancer cells disappeared from peripheral blood within 2 postoperative days. In 55 patients who underwent a curative operation, the risk for cancer recurrence (10/30; 33%) in 30 patients who did not show circulating cancer cells postoperatively was higher than that for cancer recurrence (3/25; 12%) in 25 patients with positive for circulating cancer cells (P = 0.064). As a result, the presence of blood circulating tumor cells just after surgery tends to correlate with a low rate of tumor recurrence in patients operated on for gastric cancer.

Conclusion: These findings indicate that a gastrectomy may spread gastric cancer cells into the peripheral blood from primary tumors; however, such circulating cancer cells may be destroyed within a short time. The detection of circulating cancer cells may therefore be a marker for a possibly better prognosis in patients with gastric cancer.