Significance of Circulating Tumor Cells in the Treatment of Gastric and Rectal Cancer

The primary purpose of this study is to compare both short-term and long-term treatment effect of laparoscopic vs. open approach on progressive gastric and rectal cancer, based on circulating tumor cell (CTC) test results as well as disease-free survivals, and figure out principles of laparoscopic approach for progressive gastric and rectal cancer. Secondary purpose is to establish an evaluation system for laparoscopic surgery for progressive gastric and rectal cancer treatment using CTC as a biomarker.