As the number of obesity continues to increase, surgical oncologist pay more attention to the effect of obesity on surgical outcomes and survival of digestive systemin cancers. Body mass index(BMI) is one of the most widely used measurements of obesity. Abdominal fat area (AFA) calculated by computed tomography is popular because of its validity of fat distribution. There is still no consensus which of BMI and AFA could be the more effective measurement and more accurate to evaluate effect of obesity on surgical outcomes and survival. Gastric cancer is one of the most common digestive system cancers, and gastrectomy is the primary therapeutic options.It is important to compare the different measurements(BMI or AFA) to assess obesity and effect on surgical outcome and survival for gastric cancer patients.

Standard operation procedure（SOP）

1. Preoperative evaluation Patients satisfied with inclusion/exclusion criteria will be informed to join in the clinical study and signature the inform consent.
2. Procedures: The surgical treatments is adopted total or subtotal gastrectomy according to the Japanese Gastric Cancer treatments guidelines, 2010, Version 3.
3. Postoperative recovery: Postoperative recovery period need to collect those relevant parameters of all the patients. All the relevant parameters had definitely definition in the Case Report Form of this study which included the preoperative, intraoperative and postoperative clinicopathologic characteristics.
4. Follow-up: Follow-up will last to 5-year of the postoperative period. The postoperative complications is graded by the clavian-dildo classification. The postoperative complications and quality of life (change of AFA,performance status, recurrence and overall survival)are the focus of this study.

Inclusion Criteria:

1. Preoperative endoscopy and biopsy confirmed gastric adenocarcinoma, and predictively feasible of conventional open total gastrectomy or subtotal gastrectomy;
2. Predictively resectable diseases, of preoperative staging Japanese Gastric Cancer Association 14th Edition clinical T1N0M0-T4aN+M0;
3. Age：≤75 years, or ≥18 years;
4. Without serious disease and malignance disease;
5. Without histories of abdominal surgery;
6. World Health Organization performance score ≤2, American Society of Anesthesiologists score ≤3;
7. No limit to sexual and race;
8. Informed consent required;
9. Obesity is defined as BMI≧30kg/m2 or preoperative AFA≧100cm2/cm.

Exclusion Criteria:

1. Patients with other severe complications cannot tolerate surgery: such as severe heart and lung diseases, heart function below clinical stage 2, uncontrollable hypertension, pulmonary infection, moderate to severe chronic obstructive pulmonary disease, chronic bronchitis, severe diabetes and / or renal insufficiency, severe hepatitis and / or function below the rank of CHILD B grade, and severe malnutrition, etc;
2. Patients treated with neoadjuvant chemotherapy or radiation therapy which might affect the efficacy observation;
3. Severity mental diseases;
4. Primary lesion cannot be resected in the pattern of transabdominal gastrectomy, but for Whipple's procedure, or with a transthoracic approach surgery;
5. After signature the Clinical trial agreement, patients and their agent will quit the trial.