The design of study
This study evaluates the efficacy of SL with peritoneal cytology, and determine the indications if possible.
Patients who meet the inclusion criteria will be enrolled consecutively, with their preliminary data collected using a web-based case report form. When the whole data-collecting is completed, factors associated with intra-abdominal metastasis will be analyzed by multivariate Cox regression model. Receiver-operator characteristic (ROC) will be used to find out risk factors of intra-abdominal metastasis. Figure 1 shows the CONSORT diagram.
Recruitment
Patients with pathologically confirmed gastric adenocarcinoma are recruited. If the patient meets all inclusion criteria, following data will be recorded: basic information including age, gender, height, body weight et al., clinical information including CT stage(enhanced CT is mandatory required), EUS stage, result of blood examinations such as tumor marker (CEA, CA19-9, CA72-4, CA12-5), blood cell count, albumin et al. If there been any differences between CT & EUS, it is required to record them separately.
Staging laparoscopy
If the patient is confirmed at stage cT2-4bN0-3 M0, which means no sign of distant metastasis detected by CT/EUS, he/she undergoes SL. Following data will be recorded: intraoperative finding including the peritoneal dissemination, and the peritoneal lavage; video of surgery and pictures demonstrating the extent of peritoneal dissemination is required.
Follow-up
Postoperative hospital stay and complications will be recorded, the follow-up time will be 30 days after surgery. Only those who undergoes DL alone will be included into safety analysis since the complications will be confused if the patient undergo radical surgery immediately after SL.
Study endpoint
The primary target of this study is to obtain the result of SL. Either peritoneal dissemination or a positive result of cytological examination will be recorded as a positive result. If the pathological or cytological examination describes “suspicious”, the result will be characterized as positive, consistent with our current practice.
The secondary aim is to evaluate the safety of SL.
Selection of candidate patients
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1)
Age ≥ 18;
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2)
Histological confirmed diagnosis of primary gastric carcinoma (including esophagus-gastric junction).
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3)
Karnofsky score ≥ 70;
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4)
Abdominally enhanced spinal CT and endoscopic ultrasonography (EUS) showed a clinical stage of T2-4bN0-3bM0;
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5)
Fit for radical gastrectomy or neo-adjuvant chemotherapy;
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6)
Willing to comply with protocol, and provide informed consent forum.
The exclusion criteria included:
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1.
Unfit for laparoscopic operation or general anesthesia (suspicious abdominal adhesions, severe cardiopulmonary disease, etc.);
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2.
Underwent emergency surgery to relieve obstruction, bleeding or perforation.
SL technique
SL was performed under general anesthesia. The patient is placed in a supine position. A 10-mm disposable trocar (observing hole) is inserted into the sub-umbilicus, and a 30° telescope is used. Another 10-mm trocar and a 5-mm trocar (operating hole) are inserted into the right upper quadrant and left upper quadrant, respectively. Prior to any manipulation, 250 ml of warm normal saline is infused into subphrenic space, subhepatic space, omentum, bilateral paracolic sulci and the pouch of Douglas. The irrigation should be carefully operated to avoid the primary tumor. At least 100 ml of fluid is aspirated from the subphrenic space, subhepatic space and Douglas’ pouch. The fluid is immediately sent for centrifugation and cytological examination and a systematic inspection of the abdominal cavity is performed clockwise from the right quadrant. Any suspicious lesion will be biopsied and sent for frozen pathologic examination.
Sample size
This study is a single arm OPC (objective performance criteria) design where the primary evaluation index is the positive rate of SL. Based upon literature, expected event rate is 20%, and clinical acceptable rate is above 15%. Type I error as bilateral 5%, dropout rate as 5%, power as 80%, calculated sample size is 450. The recruitment process is estimated to be completed by December 2016.
Data analysis
Clinical characteristics of the DL- and DL+ patients are compared using the Independent samples group t test and chi-square test. To determine the risk factors, all variables found to be significant by the univariate analysis are assessed by binary logistic regression analysis (Method: Backward: Wald, probability for stepwise: 0.5 for entry, 1.0 for removal). The ROC curve and AUC analyses are used to determine sensitivity, specificity, and corresponding cut-off value of each factor. All P values < .05 are considered statistically significant. All statistical analyses are carried out using the SPSS statistical software package (version 20).
