For advanced gastric cancer, surgical resection is the only curable therapeutic strategy. According to minimally invasive approach is adopted in various field of oncologic surgery, laparoscopic gastrectomy with lymph node dissection is becoming a standard not only for early gastric cancer but also for advanced gastric cancer.
The greater omentum is an organ is known to play a role in removing bacteria in the abdominal cavity as a primary defense. Complete resection of the greater omentum has been considered essential to ensure the elimination of micrometastasis during surgery for advanced gastric cancer. However, the oncological effect of total omentectomy is still lack of evidence. Especially in minimal invasive gastrectomy, total omentectomy procedure is known to increases the operating time, increase the risk of bleeding, colonic injury, and postoperative complications such as intra-abdominal abscess, ascites, anastomotic leakage, ileus and wound infections. Therefore, in the case of minimal invasive surgery in early gastric cancer, omentectomy is omitted usually or routinely. Partial omentectomy preserves the omentum more than 3cm away from the gastro-epiploic vessels. Advanced energy devices facilitate partial omentectomy during laparoscopic gastrectomy.
According to the Japanese Gastric Cancer Treatment Guidelines, partial omentectomy (omentum preservation) is feasible for T1 or T2 tumors, and total omentectomy is recommended for clinical T3 or deeper tumors. However, the National Comprehensive Cancer Network(NCCN) guideline suggests total omentectomy and the European Society for Medical Oncology(ESMO) guideline does not mentioned about it.
It is still controversial whether total omentectomy should be performed in advanced gastric cancer. Therefore, we aimed to verify the non-inferiority of partial omentectomy, oncologic safety compared with total omentectomy via multicenter randomized clinical trial.
Histologically proven adenocarcinoma of the stomach
Age between 20 to 85 years old
ECOG PS 0-1, ASA class I-III
Endoscopically Borrmann type I, II, III
Confirmed distant metastasis in preoperative examinations
Confirmed metastasis in abdominal cavity or distant organs during surgery
Confirmed no infiltration of the serosa layer or unable to confirm the tumor location during surgery (sT1-2)
Confirmed invasion of surrounding organs (sT4b)
Parallel
Arm I (Total omentectomy),
Procedure/SurgeryThe surgery is performed with minimal invasive surgery, and the range of the surgery is radical gastrectomy and D2 lymph node dissection. Depending on the random assignment, total omentectomy and partial omentectomy (omentum preservation) will be performed for the control group and the experimental group, respectively. Total omentectomy removes whole greater omentum, while partial omentectomy preserves the omentum more than 3cm away from the gastro-epiploic vessels. Other surgical procedures are the same as usual in both groups.
Arm II (Partial omentectomy)
Procedure/SurgeryThe surgery is performed with minimal invasive surgery, and the range of the surgery is radical gastrectomy and D2 lymph node dissection. Depending on the random assignment, total omentectomy and partial omentectomy (omentum preservation) will be performed for the control group and the experimental group, respectively. Total omentectomy removes whole greater omentum, while partial omentectomy preserves the omentum more than 3cm away from the gastro-epiploic vessels. Other surgical procedures are the same as usual in both groups.
3-year relapse free survival
Verify the non-inferiority of partial omentectomy(omentum preservation) in 3-year relapse free survival(RFS). Kaplan-Meier and log-rank tests will be used.
3-year overall survival
To compare surgical outcomes between the partial omentectomy and total omentectomy in patients with advanced gastric cancer, especially clinical T3 and T4a tumors without distant metastasis, who underwent minimal invasive radical gastrectomy and D2 lymph node dissection. Clinicopathologic features and surgical outcomes will be analyzed using an paired t-test for continuous variables and the Chi-square test or Fisher's exact test for nominal variables. In the survival analysis, the Kaplan-Meier and log-rank tests will be used. Surgical complications will be graded according to the Clavien-Dindo classification.
Estimated blood loss
To compare surgical outcomes between the partial omentectomy and total omentectomy in patients with advanced gastric cancer, especially clinical T3 and T4a tumors without distant metastasis, who underwent minimal invasive radical gastrectomy and D2 lymph node dissection. Clinicopathologic features and surgical outcomes will be analyzed using an paired t-test for continuous variables and the Chi-square test or Fisher's exact test for nominal variables. In the survival analysis, the Kaplan-Meier and log-rank tests will be used. Surgical complications will be graded according to the Clavien-Dindo classification.
Operation time
To compare surgical outcomes between the partial omentectomy and total omentectomy in patients with advanced gastric cancer, especially clinical T3 and T4a tumors without distant metastasis, who underwent minimal invasive radical gastrectomy and D2 lymph node dissection. Clinicopathologic features and surgical outcomes will be analyzed using an paired t-test for continuous variables and the Chi-square test or Fisher's exact test for nominal variables. In the survival analysis, the Kaplan-Meier and log-rank tests will be used. Surgical complications will be graded according to the Clavien-Dindo classification.
Post-operative complications (Early, and delayed complication)
To compare surgical outcomes between the partial omentectomy and total omentectomy in patients with advanced gastric cancer, especially clinical T3 and T4a tumors without distant metastasis, who underwent minimal invasive radical gastrectomy and D2 lymph node dissection. Clinicopathologic features and surgical outcomes will be analyzed using an paired t-test for continuous variables and the Chi-square test or Fisher's exact test for nominal variables. In the survival analysis, the Kaplan-Meier and log-rank tests will be used. Surgical complications will be graded according to the Clavien-Dindo classification.
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