A Phase-II Clinical Trial of Laparoscopy-Assisted Distal Gastrectomy With D2 Lymph Node Dissection for Gastric Cancer

Gastric cancer is the most common cancer in Korea; the overall age-standardized incidence rates of gastric cancer in Korea have been reported to be 69.6 per 100,000 among males and 26.8 per 100,000 among females in 2000.

Treatment modalities for resectable gastric cancer include endoscopic mucosal resection (EMR), laparoscopy-assisted gastrectomy (LAG) and conventional open gastrectomy. Laparoscopic cancer surgery has been reported to be an acceptable alternative to open surgery in patients with colorectal cancer. However, in gastric cancer, laparoscopic surgery has not yet been validated and, thus, is performed only in a limited number of patients with early gastric cancer; this is due to the technical difficulty in systematic lymph node dissection. For the treatment of advanced gastric cancer (AGC), in countries including Korea and Japan, gastrectomy with D2 lymph node dissection has been the standard operation. With the recent progress in diagnostic techniques, accumulation of experience with laparoscopy-assisted distal gastrectomy (LADG) for early gastric cancer and the increasing interest in a better quality of life, there has been an effort to apply minimally invasive techniques to the treatment of AGC. However, there has been no clinical trial to test the oncological feasibility of LADG with D2 lymph node dissection. There is only one phase-II study that evaluated whether the morbidity associated with LADG was higher than that of open gastrectomy.

Before the indications for LADG can be extended to include patients with advanced cancer, the status of surgical expertise for complete D2 lymph node dissection requires investigation using a prospective clinical study design. If this approach is shown to be feasible, a randomized prospective clinical trial, to compare survival and other surgical outcomes, would be the next step in validating this technique for this group of patients.

This study is to be performed according to the Helsinki Declaration. The study was approved by the Ethics Subcommittee at the National Cancer Center for Research Involving Human Subjects (no. NCCCTS-2005181). All patients will be provided written informed consent before entering the study.

Sample size The sample size was based on the alpha error at 0.05 and 90% of power and the accepted margin of the difference in the compliance rate at 10% based on a non-inferiority test. The target was chosen from the primary end point of the study. For the patients who underwent LADG with D2 lymph node dissection, the compliance rate-defined as cases in which there was no more than one missing lymph node station according to the guidelines of "The Japanese Research Society for Gastric Cancer" (JRSGC) lymph node grouping,11,12-was set up to 55%; for the patients with open distal gastrectomy with D2 lymph node dissection, it was 66%, based on a pilot study. We performed a pilot study to determine the compliance rate in 100 cases of open distal gastrectomy with D2 lymph node dissection before enrollment started. When the data was used for the formula, the total sample size required was determined to be 60 patients. When we added 10% for expected follow-up loss, the total sample size was calculated to be 66 patients.