Gastric cancer is one of mostly common digestive tract tumors. With increasingly advanced diagnostic technology, more and more gastric cancer patients would be diagnosed in the early stage. In particular, in Japan, early-stage gastric cancer takes a large proportion; while in China, the proportion of early-stage gastric cancer is up to appropriately 15%. In addition, increasingly developed microsurgical technique contributes to the application of microsurgery of early-stage gastric cancer[11-12]. Laparoscopic radical gastrectomy provides a new alternative to gastric cancer patients. But since emergence of laparoscopic gastrectomy till now, there are two greatly different viewpoints regarding the safety and therapeutic efficacy of laparoscopic gastrectomy[13]. Some scholars reported that laparoscopic gastrectomy can alleviate patients’ wound, shorten the length of hospital stay, and acquire the same middle- and long-term therapeutic efficacy as open gastrectomy, but some others reported that laparoscopic gastrectomy is complicated, takes longer operating time, may cause more postoperative complications, is difficult to thoroughly remove lymph nodes, and influences therapeutic effects[14-15]. Evidence exists that laparoscopic gastrectomy provides the therapeutic efficacy and safety the same as open gastrectomy, but prospective, randomized, controlled studies involving larger sample cases are lacked. For this reason, this Meta analysis was performed.
The five papers included in this Meta analysis are all prospective, randomized, controlled trials, but Jadad scoring results demonstrated that randomization was not clearly described, and blinding method was not described, which lead to the low scores. Only Hayashi et al[8] and Lee et al[9] rationally described randomization and allocation concealment, but Lee et al[9] did not describe the withdrawals and dropouts. All these result in non-ideal Jadad scores. Poor literature quality is not conducive to the final results of Meta analysis. This indicates that scholars would scientifically, rationally describe experimental design in future related studies.
Heterogeneity analysis demonstrated that controversy to different extents exists in four of eight outcome measures, and difference in operating time and intraoperative blood loss would be related to different modes to remove lymph node. Huscher et al[7] and Lee et al[9] used D2 lymph node dissection, while Kitano et al[6], Hayashi et al[8], and Kim et al[10] used D1 lymph node dissection. These directly lead to difference in operating time and intraoperative blood loss. The differences in time to resumption of oral intake and length of hospital stay may be related to different scoring criteria.
Sensitivity analysis demonstrated that publication bias to different extents exist in each index, in particular in intraoperative blood loss. After exclusion of report from Lee et al[9] (findings greatly different from the other four papers), there was no obvious changes in new statistical results. Laparoscopic gastrectomy produces obviously reduced intraoperative blood loss than open gastrectomy.
Subgroup analysis demonstrated that in D1 lymph node dissection, laparoscopic gastrectomy greatly reduces intraoperative blood loss than open gastrectomy, which indicates that laparoscope exerts advantages in D1 lymph node dissection. In D2 lymph node dissection, laparoscopic gastrectomy results in less blood less, but there was no statistical significance. This is likely to be different from reports from Huscher et al[7] and Lee et al[9], but a small sample size is a possible cause. Clinical studies involving larger sample cases are needed to identify this.
Meta analysis from this paper demonstrate that laparoscopic gastrectomy produces significantly less intraoperative blood loss than open gastrectomy, which is consistent with some reports[6-8, 10, 16], but is different from the report from Lee et al[9]. This may be related to different surgical methods or techniques, but less intraoperative blood loss does not improve postoperative complications or postoperative mortality rate. Results from this Meta analysis indicate that laparoscopic gastrectomy provides equivalent effects on postoperative complications, postoperative mortality rate, and tumor recurrence during radical gastrectomy for treatment of early-stage gastric cancer. This suggests that laparoscopic gastrectomy for early-stage gastric cancer is feasible and safe.
Lymph node dissection is one of focuses on the controversy of gastrectomy for treatment of gastric cancer. Results from this Meta analysis demonstrated that laparoscopic gastrectomy for early-stage gastric cancer would reduce averagely 4.79 lymph nodes, but this does not increase tumor recurrence. Therefore, it is necessary to widely remove lymph nodes, in particular for patients with early-stage gastric cancer, further studies are needed, because for intramucosal carcinoma, lymph node metastasis rate is 2%-5%, while for submucosal carcinoma, the metastasis rate is 11%-12%[17], but only 3.5%[18] of patients showed lymph node metastasis to the second station. D2 lymph node dissection is always considered a standard surgical mode, but it is widely disputed[19-22]. Evidence exists that D2 lymph node dissection for gastric cancer patients cannot enhance 5-year survival rate, instead increase postoperative complications and mortality rate[23].
Laparoscopic gastrectomy takes longer operating time than open gastrectomy, which is consistent with other reports, but the prolonged operating time does not obviously increase postoperative complications or postoperative mortality rate, which occurs possibly because of non-mature technique in laparoscopic gastrectomy. With increasingly improved technique and gradually developed surgical instruments, this gap would be gradually narrowed. Statistical results demonstrated that laparoscopic gastrectomy could reduce the time to resumption of oral intake (averagely 0.85 day) than open gastrectomy, but there was no statistical significance, which is different from related report[24]. This occurs possibly because long operating time produces effects on gastrointestinal tract functions. Large sample sized, multi-center, prospective, randomized, controlled trials would acquire more precise conclusion. In addition, the majority of five papers included in this Meta analysis used B-I anastomosis of digestive tract. This changes the physiological structure minimally. But related reports indicate that a Roux-en-Y anastomosis is more suitable for early gastric cancer than B-I anastomosis[25]. This is because patients that underwent Roux-en Y anastomosis rarely present heartburn, bile regurgitation, and inflammations of gastric remnant[26]. Therefore, which anastomosis should be selected in reconstruction of digestive tract should be further investigated.
Results from this Meta analysis demonstrate that laparoscopic gastrectomy for treatment of early-stage gastric cancer can reduce intraoperative blood loss, in particular for D1 lymph node dissection, and attain equivalent effects on postoperative complications, postoperative mortality rate, and tumor recurrence, but it takes longer operating time than open gastrectomy owing to complicated laparoscopic techniques and constraints of instrument developments, which requires strict selection of patients and strict professional training to surgeons. Based on accumulative data, the indications for laparoscopic gastrectomy are gastric cancer patients with tumor infiltration depth within T2[27]. Yu et al[28] and Huscher et al[29] reported that laparoscopic D2 radical gastrectomy can acquire radical cure for progressive gastric cancer patients who present tumor infiltrating placenta percreta area < 10 cm2. Laparoscopic gastrectomy is not suitable for those gastric cancer patients who present large area of placenta percreta area infiltrated, or tumor diameter > 10 cm, or lymph node metastasis foci fused or encasing important vessels and (or) tumors invading peripheral tissue organs. For progressive gastric cancer patients who present lymph nodes surrounding the stomach metastasized to the second station and need radical gastric resection, open gastrectomy is suitable and can acquire radical cure, thereby enhancing patients’ 5-year survival rate[30]. However, there have been some reports regarding successful surgery for patients with stage II, even stage IIIA, gastric cancer[2]. This would put forward higher requirements for surgeons. Shimizu et al[31] reported that a skilled laparoscopic gastrectomy needs surgical practice of 30-50 cases; for a beginner, hand-assisted laparoscopic gastrectomy is the best option, because it is conducive to regional lymph node dissection and learning curve is very short[32].
