Short-Term Outcomes from a Randomized Screening Phase II Non-inferiority Trial Comparing Omentectomy and Omentum Preservation for Locally Advanced Gastric Cancer: the TOP-G Trial

Effect of omentum preservation on long-term prognosis of locally advanced gastric cancer: a systematic review and meta-analysis

BACKGROUND

The effect of omentum preservation (OP) on locally advanced gastric cancer (LAGC) remains controversial. This study aimed to investigate the long-term prognosis of LAGC patients with OP versus omentum resection (OR).

METHODS

A comprehensive search of databases including PubMed, Web of Science, Embase, and Cochrane Library was conducted up until February 2024. Statistical analysis was performed using Stata 12.0 software. The primary outcome was to assess the impact of OP on the long-term prognosis of patients with LAGC, including overall survival (OS) and recurrence-free survival (RFS).

RESULTS

A total of six case-control studies were included, encompassing a cohort of 1897 patients. The OP group consisted of 844 patients, while the OR group comprised 1053 patients. The study results showed that the OS (HR = 0.72, 95% CI: 0.58-0.90, P = 0.003) and 5-year RFS (HR = 0.79, 95% CI: 0.63-0.99, P = 0.038) in the OP group were superior to those observed in the OR group. Subgroup analysis indicated that 5-year OS (HR = 0.64, P = 0.003) and 5-year RFS (HR = 0.69, P = 0.005) in the OP group were also better than those in the OR group in Korea. However, the subgroup analysis conducted on stage T3-T4 tumors revealed no statistically significant differences in OS (P = 0.083) and 5-year RFS (P = 0.173) between the two groups.

CONCLUSION

Compared with OR, OP shows non-inferiority in patients with LAGC and can be considered a potential treatment option for radical gastrectomy.

Omentum preservation versus complete omentectomy in gastrectomy for gastric cancer (OMEGA trial): study protocol for a randomized controlled trial

BACKGROUND

Potentially curative therapy for locally advanced gastric cancer consists of gastrectomy, usually in combination with perioperative chemotherapy. An oncological resection includes a radical (R0) gastrectomy and modified D2 lymphadenectomy; generally, a total omentectomy is also performed, to ensure the removal of possible microscopic disease. However, the omentum functions as a regulator of regional immune responses to prevent infections and prevents adhesions which could lead to bowel obstructions. Evidence supporting a survival benefit of routine complete omentectomy during gastrectomy is lacking.

METHODS

OMEGA is a randomized controlled, open, parallel, non-inferiority, multicenter trial. Eligible patients are operable (ASA < 4) and have resectable (≦ cT4aN3bM0) primary gastric cancer. Patients will be 1:1 randomized between (sub)total gastrectomy with omentum preservation distal of the gastroepiploic vessels versus complete omentectomy. For a power of 80%, the target sample size is 654 patients. The primary objective is to investigate whether omentum preservation in gastrectomy for cancer is non-inferior to complete omentectomy in terms of 3-year overall survival. Secondary endpoints include intra- and postoperative outcomes, such as blood loss, operative time, hospital stay, readmission rate, quality of life, disease-free survival, and cost-effectiveness.

DISCUSSION

The OMEGA trial investigates if omentum preservation during gastrectomy for gastric cancer is non-inferior to complete omentectomy in terms of 3-year overall survival, with non-inferiority being determined based on results from both the intention-to-treat and the per-protocol analyses. The OMEGA trial will elucidate whether routine complete omentectomy could be omitted, potentially reducing overtreatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05180864. Registered on 6th January 2022.

Comparative assessment of the capability of machine learning-based radiomic models for predicting omental metastasis in locally advanced gastric cancer

The study aims to investigate the predictive capability of machine learning algorithms for omental metastasis in locally advanced gastric cancer (LAGC) and to compare the performance metrics of various machine learning predictive models. A retrospective collection of 478 pathologically confirmed LAGC patients was undertaken, encompassing both clinical features and arterial phase computed tomography images. Radiomic features were extracted using 3D Slicer software. Clinical and radiomic features were further filtered through lasso regression. Selected clinical and radiomic features were used to construct omental metastasis predictive models using support vector machine (SVM), decision tree (DT), random forest (RF), K-nearest neighbors (KNN), and logistic regression (LR). The models' performance metrics included accuracy, area under the curve (AUC) of the receiver operating characteristic curve, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). In the training cohort, the RF predictive model surpassed LR, SVM, DT, and KNN in terms of accuracy, AUC, sensitivity, specificity, PPV, and NPV. Compared to the other four predictive models, the RF model significantly improved PPV. In the test cohort, all five machine learning predictive models exhibited lower PPVs. The DT model demonstrated the most significant variation in performance metrics relative to the other models, with a sensitivity of 0.231 and specificity of 0.990. The LR-based predictive model had the lowest PPV at 0.210, compared to the other four models. In the external validation cohort, the performance metrics of the predictive models were generally consistent with those in the test cohort. The LR-based model for predicting omental metastasis exhibited a lower PPV. Among the machine learning algorithms, the RF predictive model demonstrated higher accuracy and improved PPV relative to LR, SVM, KNN, and DT models.

What are the short- and long-term abdominal consequences of an omentectomy? A systematic review

This review provides an overview regarding the abdominal effects of an omentectomy, with or without extra-peritoneal reconstructions. In general, reported complication rates were low. Short-term complications involved ileus, bowel stenosis, abdominal abscess and sepsis (range 0.0%-23%). Donor-site hernia was mainly reported as long-term complication (up to 32%) and negligible gastrointestinal complications were observed. However, the level of evidence and methodological quality are quite low with a maximum of 8.5 years follow-up.

The outcomes of laparoscopic omentum-preserving gastrectomy compared to open surgery with omentectomy in gastric cancer patients: a propensity score matched study of 249 UICC stage 0-IV gastric cancer patients

BACKGROUND

We performed a propensity score matched study comparing patients' short- and long-term results after laparoscopic omentum-preserving gastrectomy and open surgery with omentectomy with UICC stages 0-IV.

METHODS

Between 2015 and 2022, 311 patients with gastric cancer underwent surgery at the University Clinical Centre Maribor. Of these, 249 met the inclusion criteria and 198 were included in the study group after PSM.

RESULTS

Patients in both groups were well-balanced in demographic and pathological characteristics after PSM. There was no significant difference in the 5-year survival between groups (LAP: 62.2% vs. OPN: 54.4%; p = 0.950). The Cox regression model identified UICC stage and age as significant predictors for survival. In both groups, peritoneal dissemination was the most common site of recurrence. The multivariate analysis identified the UICC stage as a significant predictor for peritoneal recurrence, while omental preservation was not associated with a higher risk of peritoneal dissemination. Omentum preservation was not associated with more intestinal obstruction. Patients in the LAP group had significantly shorter hospital stays (LAP: 9(6) vs. OPN: 10(5); p = 0.009), less postoperative morbidity (LAP: 17% vs. OPN: 23.4%; p = 0.009), and significantly more extracted LNs per operation compared to open surgery (LAP: 31 ± 11 LNs vs. OPN: 25 ± 12 LNs; p = 0.002).

CONCLUSION

Based on our results, we recommend the use of laparoscopic omentum-preserving gastrectomy in patients with early and advanced gastric cancer.

Does total omentectomy prevent peritoneal seeding for advanced gastric cancer with serosal invasion?

BACKGROUND

Radical gastrectomy is composed of gastrectomy, lymph node dissection, and omentectomy. Total omentectomy (TO) is expected to reduce the incidence of peritoneal recurrence. We aimed to investigate the necessity of TO for advanced gastric cancer (AGC) with serosal invasion.

METHODS

We retrospectively reviewed 310 patients who underwent radical gastrectomy with TO and 93 patients who underwent partial omentectomy (PO) for gastric cancer with serosal invasion between August, 2005 and December, 2017. Finally, 91 patients in the PO group and 91 in the TO group were enrolled based on a 1:1 propensity-score matching analysis. We evaluated surgical and oncological outcomes, including 5-year overall and recurrence-free survival rates.

RESULTS

There was no statistically significant difference between the two groups in postoperative complications. Recurrence sites showed similar patterns in both groups, including peritoneal recurrence (PO vs. TO, 18.7% vs. 28.6%; p = 0.188). Five-year overall survival was better in the PO group (p = 0.018), while 5-year recurrence-free survival was similar in both groups (p = 0.066).

CONCLUSION

TO might not be an essential part of preventing peritoneal recurrence for AGC with serosal invasion. PO could be considered a radical gastrectomy for T4a gastric cancer.

Safety and Efficacy of Partial Omentectomy in Laparoscopic Distal Gastrectomy for pT3-T4a Stage Gastric Cancer

Purpose

Partial omentectomy (PO) has been gradually applied in laparoscopic gastrectomy for gastric cancer (GC); however, its efficacy remains unclear. The purpose of this study was to assess the safety and efficacy of PO in laparoscopic distal gastrectomy for pT3-T4a stage GC.

Patients and Methods

From June 2019 to May 2021, 108 patients with pT3 or pT4a stage GC who underwent laparoscopic distal gastrectomy were retrospectively included and divided into the PO (n=58) and total omentectomy (TO, n=50) groups. The surgical outcomes, recurrence patterns and postoperative 2-year overall survival (OS) rates were compared between the PO and TO groups.

Results

The PO group showed a shorter operation time than the TO group (183.9±21.6 vs 197.6±22.7 min, p=0.002). Less intraoperative blood loss (155.3±113.0 vs 178.8±154.4 mL, p=0.336) and intraoperative complications (5.1% vs 12.0%, p=0.298) were also observed in the PO group than in the TO group, but the difference was not significant. The numbers of retrieved lymph nodes (LNs) and metastatic LNs, postoperative hospital stays and postoperative complications in the two groups were comparable (p>0.05). Moreover, the postoperative overall recurrence rates (25.9% vs 26.0%, p=0.987) and the 2-year OS rates (63.8% vs 65.4%, p=0.437) in the PO and TO groups were also comparable. TO was not an independent prognostic factor for GC patients (HR=0.806, p=0.443).

Conclusion

In laparoscopic distal gastrectomy, PO could provide better surgical outcomes and comparable oncological outcomes compared to TO for patients with pT3-T4a stage GC, suggesting that PO may be an acceptable surgical procedure for these patients.

Omentectomy vs omentum preservation for advanced gastric cancer: A systematic review and meta-analysis

Currently, gastric cancer is the sixth most prevalent cancer in the world. The recommended treatment for advanced disease is gastrectomy with D2 lymphadenectomy. However, there is no consensus regarding the performance of an omentectomy as part of the treatment. The procedure is considered by some authors to be essential for the elimination of a micrometastasis since cells in the peritoneum prefer growing in milky spots in the omentum. On the other hand, retrospective studies demonstrated that there is the possibility that omentum preservation may not impact patients' overall survival. Therefore, the objective of this review was to quantify the effect of performing an omentectomy to determine whether it is necessary. Medline (PubMed), Embase, Cochrane, ClinicalTrials.gov and LILACS were searched up to September 2022. Selection was restricted to comparative studies in patients with advanced GC (≥T2). The certainty of evidence was assessed with GRADEPro and the risk of bias with ROBINS-I and RoB 2.0. Five cohort studies, and one randomized controlled trial (RCT) were included. The meta-analysis found that there were no significant differences between the procedures for overall survival, relapse-free survival, and peritoneal recurrence. Furthermore, in perioperative outcomes, a significant difference was only found in intraoperative bleeding, which was lower in patients who had their omentum preserved. Therefore, omentum preservation in patients with advanced gastric cancer has been shown to have no inferior results than resection in long-term outcomes.

The concept of developmental anatomy: the greater omentum should be resected in right-sided colon cancer?

BACKGROUND

The greater omentum is derived from the foregut, and the right hemicolon is derived from the midgut based on developmental anatomy. This study aimed to investigate whether the greater omentum should be resected in laparoscopic complete mesocolic excision based on developmental anatomy for right-sided colon cancer.

METHODS

A total of 183 consecutive patients with right-sided colon cancer were recruited in this study between February 2020 and July 2022. Ninety-eight patients underwent standard laparoscopic complete mesocolic excision surgery (CME group). The presence of isolated tumor cells and micrometastases was detected in resected greater omentum by the HE staining and immunohistochemistry analysis. Based on developmental anatomy, laparoscopic CME surgery with greater omentum preservation (DACME group) was proposed and performed on 85 right-sided colon cancer patients. To overcome selection bias, we performed a 1:1 match between two groups using four variables: age, sex, BMI, and ASA scores.

RESULTS

No isolated tumor cells and micrometastases were found in the resected greater omentum specimen in the CME group. After the propensity score, 81 pairs were balanced and analyzed. Patients in the DACME group showed shorter operative time (194.9 ± 16.4 min vs.201.5 ± 11.5 min, p = 0.002), less blood loss (23.5 ± 24.7 ml vs.33.6 ± 26.3 ml, p = 0.013), and the shorter hospital stays (9.6 ± 1.7 days vs.10.3 ± 2.0 days, p = 0.010) compared with patients in the CME group. In addition, patients in the DACME group had a lower incidence of postoperative complications (4.9% vs.14.8%, p = 0.035) than patients in the CME group.

CONCLUSION

The greater omentum should be preserved during right-sided colon cancer surgery, laparoscopic CME surgery based on developmental anatomy is technically safe and feasible for right-sided colon cancer.

Current standards of surgical management of gastric cancer: an appraisal

PURPOSE

Gastric cancer (GC) is the fifth most common malignancy worldwide and portends a grim prognosis due to a lack of appreciable improvement in 5-year survival. We aimed to analyze the available literature and summarize the current standards of surgical care for curative and palliative intent treatment of GC.

METHODS

We conducted a systematic search on the PubMed database for studies on the management of GC.

RESULTS

Endoscopic resection is an acceptable treatment option for T1a tumors. The role of optimal resection margin for GC remains unclear. D2 lymph node dissection remains the standard of care with splenectomy needed selectively for splenic hilum involvement. A distal pancreatic resection should be avoided. The advantage of bursectomy and omentectomy in GC surgery is not clear. Multi-visceral resection may be considered for locally advanced GC in carefully selected patients. Minimally invasive approaches are non-inferior to open surgery. Surgery should be abandoned prior even in metastatic GC within the frame of multimodal therapy approach.

CONCLUSION

Various trials have conclusively shown improved patient outcomes when well-established surgical standards are followed.

Gastrectomy with or without Complete Omentectomy for Advanced Gastric Cancer: A Meta-Analysis

Background and Objectives: Surgery remains the only possible curative treatment for advanced gastric cancer (AGC). Peritoneal metastases are estimated to occur in approximately 55–60% AGC patients. Greater omentum is the most common metastatic area in AGC. At present, omentectomy alone or bursectomy are usually carried out during gastric cancer surgery. We performed a meta-analysis in order to evaluate long-term and short-term outcomes among AGC patients, who have undergone radical gastrectomy with or without complete omentectomy (CO). Materials and Methods: We performed a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Meta-analysis was performed by use of RevMan (Computer program) Version 5.4. Results: The eight included studies covered an approximately 20 years long study period (2000–2018). Almost all included studies were retrospective ones and originated from Asian countries. Meta-analysis indicated gastrectomy without CO as significantly associated with longer 3-year (RR: 0.94, 95% CI: 0.90–0.98, p = 0.005) and 5-year overall survivals (OS) (RR: 0.93, 95% CI: 0.88–0.98, p = 0.007). Moreover, we found longer operative time (MD: 24.00, 95% CI: −0.45–48.45, p = 0.05) and higher estimated blood loss (MD: 194.76, 95% CI: 96.40–293.13, p = 0.0001) in CO group. Conclusions: Non-complete omentectomy (NCO) group had a statistically greater rate in 3-year and 5-year OSs than the CO group, while the CO group had significantly longer operative time and higher estimated blood loss than the NCO group. Further randomized, possibly multi-center trials may turn out of paramount importance in confirming our results.

Should total omentectomy be performed for advanced gastric cancer?: The role of omentectomy during laparoscopic gastrectomy for advanced gastric cancer

BACKGROUND

In the era of minimally invasive surgery, laparoscopic partial omentectomy (LPO) has seen widespread use as a curative surgical procedure for early gastric cancer. However, scientific evidence of the extent of omentectomy during laparoscopic gastrectomy remains unclear for advanced gastric cancer (AGC).

METHODS

We analyzed 666 eligible patients who underwent laparoscopic gastrectomy for AGC with curative intent between 2014 and 2018. Surgical outcome and postoperative prognosis were compared between LPO and laparoscopic total omentectomy (LTO) groups after 2:1 propensity score matching with age, sex, body mass index, tumor size, pT stage, pN stage, gastrectomy type, and clinical T stage as covariates.

RESULTS

After extensive matching, there was no significant difference in pathologic or clinical stages between the LPO (n = 254) and LTO (n = 177) groups. LPO provided a significantly shorter operation time than LTO (199.2 ± 64.8 vs. 248.1 ± 68.3 min, P < 0.001). Pulmonary complication within postoperative 30 days was significantly lower in the LPO group (4.4 vs. 10.3%, P = 0.018). In multivariate analysis, LTO was the independent risk factor for pulmonary complication (odds ratio [OR] 2.53, 95% confidence interval [95% CI] 1.12-5.73, P = 0.025), which became more obvious in patients with a Charlson's comorbidity index of 4 or higher (OR 27.43, 95% CI 1.35-558.34, P = 0.031). The 5-year overall survival rate (OS) and 3-year recurrence-free survival (RFS) rates were not significantly different between the two groups, even after stage stratification.

CONCLUSION

LPO provided significantly shorter operation time and less pulmonary complication than LTO without compromising 5-year OS and 3-year RFS for AGC. LTO was the independent risk factor for pulmonary complications, which became more evident in patients with severe comorbidities.

Pattern of lymph node metastases in gastric cancer: a side-study of the multicenter LOGICA-trial

BACKGROUND

The relation between gastric cancer characteristics and lymph node (LN) metastatic patterns is not fully clear, especially following neoadjuvant chemotherapy (NAC). This study analyzed nodal metastatic patterns.

METHODS

Individual LN stations were analyzed for all patients from the LOGICA-trial, a Dutch multicenter randomized trial comparing laparoscopic versus open D2-gastrectomy for gastric cancer. The pattern of metastases per LN station was related to tumor location, cT-stage, Lauren classification and NAC.

RESULTS

Between 2015-2018, 212 patients underwent D2-gastrectomy, of whom 158 (75%) received NAC. LN metastases were present in 120 patients (57%). Proximal tumors metastasized predominantly to proximal LN stations (no. 1, 2, 7 and 9; p < 0.05), and distal tumors to distal LN stations (no. 5, 6 and 8; OR > 1, p > 0.05). However, distal tumors also metastasized to proximal LN stations, and vice versa. Despite NAC, each LN station (no. 1-9, 11 and 12a) showed metastases, regardless of tumor location, cT-stage, histological subtype and NAC treatment, including station 12a for cT1N0-tumors. LN metastases were present more frequently in diffuse versus intestinal tumors (66% versus 52%; p = 0,048), but not for cT3-4- versus cT1-2-stage (59% versus 51%; p = 0.259). However, the pattern of LN metastases was similar for these subgroups.

CONCLUSIONS

The extent of lymphadenectomy cannot be reduced after NAC for gastric cancer. Although the pattern of LN metastases is related to tumor location, all LN stations contained metastases regardless of tumor location, cT-stage (including cT1N0-tumors), histological subtype, or NAC treatment. Therefore, D2-lymphadenectomy should be routinely performed during gastrectomy in Western patients.

Gastrectomy with omentum preservation versus gastrectomy with omentectomy for locally advanced gastric cancer: A systematic review and meta-analysis

BACKGROUND

Omentectomy has been traditionally a part of standard radical gastrectomy. Its clinical benefit for locally advanced gastric cancer (LAGC) remains controversial. This study aimed at evaluating the impact of gastrectomy with omentum preservation (GOP) on survival, recurrence, surgical outcomes and postoperative complications by comparing with gastrectomy with omentum resection (GOR).

METHODS

Original studies comparing GOP with GOR in LAGC were searched. Meta-analysis was performed using RevMan 5.4.

RESULTS

Seven studies involving 1879 patients were analyzed. Compared with GOR, GOP achieved significantly better overall survival (HR = 0.75 [0.60, 0.95], P = 0.01), with similar relapse-free survival (HR = 0.84 [0.68, 1.03], P = 0.10). The two groups had similar total recurrence rate (OR = 0.86 [0.68, 1.08], P = 0.19) and no significant differences in rates of peritoneal, hematogenous, locoregional or distant lymph node recurrences. GOP had significantly less blood loss (MD = -83 [-139, -28] ml, P = 0.003) and tended to have shorter operation time (MD = -28 [-58, 2] min, P = 0.06), with similar harvested number of lymph nodes (MD = -0.4 [-2.6, 1.8], P = 0.70). The incidences of total all grade and major complications were similar in GOP and GOR (all grade: 31.8% vs. 30.3%, OR = 1.08 [0.79, 1.46], P = 0.64; major: 9.2% vs. 10.1%, OR = 1.14 [0.55, 2.34], P = 0.73). There were no significant differences in incidences of complication or postoperative mortality.

CONCLUSIONS

Omentum preservation did not affect curability or survival in LAGC. These findings require validation in randomized controlled trials with large sample sizes.

Gastrectomy with or without omentectomy for gastric cancer: A systematic review and meta-analysis

BACKGROUND

Omentectomy is conventionally performed in the procedure of gastrectomy for gastric cancer. However, the clinical value and importance of omentectomy remain unclear. This meta-analysis investigated the benefits and safety of gastrectomy with or without omentectomy for patients with gastric cancer.

METHODS

A literature search was conducted in PubMed, Embase, and the Cochrane Library for studies comparing complete omentectomy with omentum preservation or partial omentectomy. Primary outcomes were overall survival, relapse-free survival, and incidences of recurrence and complications, whereas secondary outcomes were the total length of operation and the amount of blood loss.

RESULTS

Nine studies involving 3,561 patients were included. Our meta-analysis revealed no significant differences between omentectomy and omentum preservation in terms of the 5-year overall survival (risk ratio [RR] = 0.95, 95% confidence interval [CI] = 0.89-1.01), 5-year relapse free survival (RR: 0.96, 95% CI: 0.89-1.03), incidence of recurrence in the peritoneum or other visceral organs (RR: 1.13, 95% CI: 0.80-1.60 and RR: 1.06, 95% CI: 0.78-1.45, respectively), and incidence of complications (RR: 1.15, 95% CI: 0.89-1.50). Moreover, omentum preservation significantly reduced the total length of operation (mean difference [MD] 25.70, 95% CI: 3.23-48.17) and the amount of blood loss (MD: 56.29, 95% CI: 14.02-98.56).

CONCLUSION

Omentectomy may not be necessary and can be omitted during gastrectomy for gastric cancer.

Partial Versus Total Omentectomy in Patients with Gastric Cancer: A Systemic Review and Meta-Analysis

Background: Surgical treatment is the key to cure localized gastric cancer. There is no strong evidence that supports the value of omentectomy. Thus, a meta-analysis was conducted to compare the safety and efficiency of partial and total omentectomy in patients with gastric cancer. Methods: PubMed, Embase, and Cochrane Library databases were searched. All studies that compared total and partial omentectomy as treatments for gastric cancer were included. The primary outcomes were patients' overall survival and disease-free survival, while the secondary outcomes were perioperative outcome and postoperative complications. Results: A total of nine studies were examined, wherein 1043 patients were included in the partial omentectomy group, and 1995 in the total omentectomy group. The partial omentectomy group was associated with better overall survival (hazard ratio: 0.80, 95% CI: 0.66 to 0.98, p = 0.04, I² = 0%), shorter operative time, and lesser blood loss than the total omentectomy group. In addition, no statistically significant difference was observed in the number of dissected lymph nodes, length of hospital stays, complication rate, and disease-free survival. Conclusions: Our results show that, compared with total omentectomy in gastric cancer surgery, partial omentectomy had non-inferior oncological outcomes and comparable safety outcomes.

Efficacy of Omentum-Preserving Gastrectomy for Patients With Gastric Cancer: A Systematic Review and Meta-Analysis

Background

Complete omentectomy is considered to be essential in the radical gastrectomy for gastric cancer (GC), but its clinical benefit remains unclear. This study aims to evaluate the efficacy of omentum-preserving gastrectomy (OPG) for patients with GC.

Methods

Studies comparing the surgical and oncological outcomes of OPG and gastrectomy with complete omentectomy (GCO) for GC up to March 2021 were systematically searched from PubMed, Web of Science, Embase, and Cochrane Library. A pooled analysis was performed for the available data regarding the baseline features, surgical and oncological outcomes. The RevMan 5.3 software was used to perform the statistical analysis. Quality evaluation and publication bias were also conducted.

Results

Nine studies with a total of 3335 patients (1372 in the OPG group and 1963 in the GCO group) undergoing gastrectomy were included. In the pooled analysis, the baseline data in two groups were all comparable (p > 0.05). However, the OPG group was associated with shorter operative time (MD = −18.67, 95% CI = −31.42 to −5.91, P = 0.004) and less intraoperative blood loss (MD = −38.09, 95% CI = −53.78 to −22.41, P < 0.00001) than the GCO group. However, the number of dissected lymph nodes (MD = 2.16, 95% CI = −0.61 to 4.93, P = 0.13), postoperative complications (OR = 0.92, 95% CI = 0.74 to 1.15, p = 0.47), overall recurrence rate (OR = 0.83, 95% CI = 0.66 to 1.06, p = 0.14), peritoneal recurrence rate (OR = 0.91, 95% CI = 0.65 to 1.29, p = 0.60), 3-year relapse-free survival (RFS) rate (OR = 1.40, 95% CI = 0.86 to 2.27, p = 0.18), and 5-year RFS rate (OR = 1.21, 95% CI = 0.95 to 1.55, p = 0.12) of the two groups were comparable.

Conclusions

OPG might be an oncologically safe procedure with better surgical outcomes for patients with GC than GCO. However, high-quality randomized controlled trials are needed to confirm this benefit.

Efficiency of complete omentectomy in patients with resectable gastric cancer: a meta‑analysis and systematic review

Background

We performed a meta-analysis to investigate the efficacy of complete omentectomy (CO) in patients undergoing radical gastrectomy for gastric cancer.

Methods

We conducted a literature search in PubMed, Web of Science, and the Cochrane Library databases for clinical research that compared CO with non-complete omentectomy (NCO). These articles were published prior to April 2021. Overall survival (OS) rates, relapse-free survival (RFS) rates, recurrence rates, operation times, estimates of blood loss, numbers of harvested lymph nodes, complications, and lengths of hospital stays were compared using relative risks (RRs) and weighted mean differences (WMDs). RevMan 5.3 software was used for statistical analysis.

Results

Nine studies that included 3329 patients (1960 in the CO group) and 1369 in the NCO group comprised the analysis. The meta-analysis showed that CO was associated with a decreased 3-year OS rate (RR = 0.94, 95% CI 0.90–0.98, P = 0.005) and 5-year OS rate (RR = 0.93, 95% CI 0.88–0.98, P = 0.007). However, it was not associated with the 3-year RFS rate (RR = 0.97, 95% CI 0.90–1.04, P = 0.44), 5-year RFS (RR = 0.98, 95% CI 0.90–1.06, P = 0.60), or recurrence rate (RR = 1.17, 95% CI 0.95–1.45, P = 0.15) compared to the NCO group. For surgical-related outcomes, significant heterogeneity existed between the studies. Compared to the NCO group, CO was found to be associated with significantly more estimated blood loss (WMD = 250.90, 95% CI 105.90–396.28, P = 0.0007) and less harvested lymph nodes (WMD = − 3.59, 95% CI − 6.88, − 0.29, P = 0.03). Although, there was no significant difference in the surgical time (WMD = 15.93, 95% CI − 0.21, 32.07, P = 0.05). No statistically significant differences were observed in the rates of overall (P = 0.79) and major complications (P = 0.90), or the lengths of hospital stays (P = 0.11) between the two groups.

Conclusions

Based on the available evidence, CO is not superior to NCO in terms of survival. CO is not recommended as a routine surgery for gastric cancer. Future well-designed high-quality RCTs are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-01921-3.