Omentum preservation as an oncologically comparable and surgically superior alternative to total omentectomy during radical gastrectomy for T3-T4 gastric cancer

Gastric Cancer Surgery: Balancing Oncological Efficacy against Postoperative Morbidity and Function Detriment

Significant progress has been made in the surgical management of gastric cancer over the years, and previous discrepancies in surgical practice between different parts of the world have gradually lessened. A transition from the earlier period of progressively more extensive surgery to the current trend of a more tailored and evidence-based approach is clear. Prophylactic resection of adjacent anatomical structures or neighboring organs and extensive lymph node dissections that were once assumed to increase the chances of long-term survival are now performed selectively. Laparoscopic gastrectomy has been widely adopted and its indications have steadily expanded, from early cancers located in the distal part of the stomach, to locally advanced tumors where total gastrectomy is required. In parallel, function-preserving surgery has also evolved and now constitutes a valid option for early gastric cancer. Pylorus-preserving and proximal gastrectomy have improved the postoperative quality of life of patients, and sentinel node navigation surgery is being explored as the next step in the process of further refining the minimally invasive concept. Moreover, innovative techniques such as indocyanine green fluorescence imaging and robot-assisted gastrectomy are being introduced in clinical practice. These technologies hold promise for enhancing surgical precision, ultimately improving the oncological and functional outcomes.

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.

Normal saline remodels the omentum and stimulates its receptivity for transcoelomic metastasis

The omentum contains immune cell structures called milky spots that are niches for transcoelomic metastasis. It is difficult to remove the omentum completely, and there are no effective strategies to minimize the risk of colonization of preserved omental tissues by cancer cells that circulate in the peritoneal fluid. Normal saline is commonly administered into the peritoneal cavity for diagnostic and intraoperative lavage. Here we show that normal saline, when administered into the peritoneal cavity of mice, is prominently absorbed by the omentum, exfoliates its mesothelium, and induces expression of CX3CL1, the ligand for CX3CR1, within and surrounding the omental vasculature. Studies using CX3CR1-competent and CX3CR1-deficient mice showed that the predominant response in the omentum following saline administration is an accumulation of CX3CR1+ monocytes/macrophages that expand milky spots and promote neoangiogenesis within these niches. Moreover, saline administration promoted the implantation of cancer cells of ovarian and colorectal origin onto the omentum. By contrast, these deleterious effects were not observed following i.p. administration of lactated Ringer's solution. Our findings suggest that normal saline stimulates the receptivity of the omentum for cancer cells and that the risk of colonization can be minimized by using a biocompatible crystalloid for lavage procedures.

Development and validation of a CT radiomics and clinical feature model to predict omental metastases for locally advanced gastric cancer

""We employed radiomics and clinical features to develop and validate a preoperative prediction model to estimate the omental metastases status of locally advanced gastric cancer (LAGC). A total of 460 patients (training cohort, n = 250; test cohort, n = 106; validation cohort, n = 104) with LAGC who were confirmed T3/T4 stage by postoperative pathology were continuously collected retrospectively, including clinical data and preoperative arterial phase computed tomography images (APCT). Dedicated radiomics prototype software was used to segment the lesions and extract features from the preoperative APCT images. The least absolute shrinkage and selection operator (LASSO) regression was used to select the extracted radiomics features, and a radiomics score model was constructed. Finally, a prediction model of omental metastases status and a nomogram were constructed combining the radiomics scores and selected clinical features. An area under the curve (AUC) of the receiver operating characteristic curve (ROC) was used to validate the capability of the prediction model and nomogram in the training cohort. Calibration curves and decision curve analysis (DCA) were used to evaluate the prediction model and nomogram. The prediction model was internally validated by the test cohort. In addition, 104 patients from another hospital's clinical and imaging data were gathered for external validation. In the training cohort, the combined prediction (CP) model (AUC 0.871, 95% CI 0.798-0.945) of the radiomics scores combined with the clinical features, compared with clinical features prediction (CFP) model (AUC 0.795, 95% CI 0.710-0.879) and radiomics scores prediction (RSP) model (AUC 0.805, 95% CI 0.730-0.879), had the better predictive ability. The Hosmer-Lemeshow test of the CP model showed that the prediction model did not deviate from the perfect fitting (p = 0.893). In the DCA, the clinical net benefit of the CP model was higher than that of the CFP model and RSP model. In the test and validation cohorts, the AUC values of the CP model were 0.836 (95% CI 0.726-0.945) and 0.779 (95% CI 0.634-0.923), respectively. The preoperative APCT-based clinical-radiomics nomogram showed good performance in predicting omental metastases status in LAGC, which may contribute to clinical decision-making.

Is Total Omentectomy Mandatory in T3 and T4a Gastric Cancer for Laparoscopic Distal Gastrectomy?

BACKGROUND

Despite the lack of strong evidence, total omentectomy (TO) remains the recommended procedure for gastric cancer (GC) for T3 or deeper tumors. Partial omentectomy (PO) has recently become a preferred procedure owing to its simplicity during laparoscopic distal gastrectomy (LDG); however, the oncological role of PO needs to be elucidated.

METHODS

Overall, 341 patients with T3 or T4a GC who had undergone LDG between 2009 and 2016 were divided into TO (n = 167) and PO (n = 174) groups. Propensity matching was performed with respect to covariance age, sex, T and N stage, tumor size, and degree of tumor differentiation. Clinicopathological characteristics and long-term follow-up data were analyzed for both groups.

RESULTS

After successful propensity matching, both groups included 107 patients. In a matched cohort, no significant difference in clinicopathologic features and short-term surgical outcomes was observed between the two groups. Furthermore, no significant difference in relapse-free survival (RFS; p = 0.201) and peritoneal seeding-free survival (PSFS; p = 0.094) was observed. However, tumor recurrence as peritoneal metastasis occurred in 5 (4.7%) patients in the PO group and 13 (12.1%) patients in the TO group. In Cox proportional hazards analysis, omentectomy was not identified as a significant factor for RFS, PSFS, and overall survival; however, advanced N and T4a stage were considered significant factors for RFS and PSFS, respectively.

CONCLUSIONS

PO may be adopted during the LDG of T3 or T4a GC without definite gross serosal exposure. More large-scale evidence or prospective study is recommended.

Korean Practice Guidelines for Gastric Cancer 2022: An Evidence-based, Multidisciplinary Approach

Gastric cancer is one of the most common cancers in Korea and the world. Since 2004, this is the 4th gastric cancer guideline published in Korea which is the revised version of previous evidence-based approach in 2018. Current guideline is a collaborative work of the interdisciplinary working group including experts in the field of gastric surgery, gastroenterology, endoscopy, medical oncology, abdominal radiology, pathology, nuclear medicine, radiation oncology and guideline development methodology. Total of 33 key questions were updated or proposed after a collaborative review by the working group and 40 statements were developed according to the systematic review using the MEDLINE, Embase, Cochrane Library and KoreaMed database. The level of evidence and the grading of recommendations were categorized according to the Grading of Recommendations, Assessment, Development and Evaluation proposition. Evidence level, benefit, harm, and clinical applicability was considered as the significant factors for recommendation. The working group reviewed recommendations and discussed for consensus. In the earlier part, general consideration discusses screening, diagnosis and staging of endoscopy, pathology, radiology, and nuclear medicine. Flowchart is depicted with statements which is supported by meta-analysis and references. Since clinical trial and systematic review was not suitable for postoperative oncologic and nutritional follow-up, working group agreed to conduct a nationwide survey investigating the clinical practice of all tertiary or general hospitals in Korea. The purpose of this survey was to provide baseline information on follow up. Herein we present a multidisciplinary-evidence based gastric cancer guideline.

Accuracy of preoperative clinical staging for locally advanced gastric cancer in KLASS-02 randomized clinical trial

Purpose

The discrepancy between preoperative and final pathological staging has been a long-standing challenge for the application of clinical trials or appropriate treatment options. This study aimed to demonstrate the accuracy of preoperative staging of locally advanced gastric cancer using data from a large-scale randomized clinical trial.

Materials and methods

Of the 1050 patients enrolled in the clinical trial, 26 were excluded due to withdrawal of consent (n = 20) or non-surgery (n = 6). The clinical and pathological staging was compared. Risk factor analysis for underestimation was performed using univariate and multivariate analyses.

Results

Regarding T staging by computed tomography, accuracy rates were 74.48, 61.62, 58.56, and 85.16% for T1, T2, T3 and T4a, respectively. Multivariate analysis for underestimation of T staging revealed that younger age, ulcerative gross type, circular location, larger tumor size, and undifferentiated histology were independent risk factors. Regarding nodal status estimation, 54.9% of patients with clinical N0 disease were pathologic N0, and 36.4% of patients were revealed to have pathologic N0 among clinical node-positive patients. The percentage of metastasis involvement at the D1, D1+, and D2 lymph node stations significantly increased with the advanced clinical N stage. Among all patients, 29 (2.8%), including 26 with peritoneal seeding, exhibited distant metastases.

Conclusions

Estimating the exact pathologic staging remains challenging. A thorough evaluation is mandatory before treatment selection or trial enrollment. Moreover, we need to set a sufficient case number when we design the clinical trial considering the stage migration.

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.

Occult Omental Metastasis in Gastric Adenocarcinoma: An Analysis of Incidence, Predictors, and Outcomes

Negine PaulIntroduction  Traditionally, the concept of complete omentectomy during gastric resection for cancer was based on lymphatic drainage and the occurrence of occult omental metastasis (OM). However, recent emerging evidence has challenged this concept of complete omentectomy. We, therefore, aim to find the incidence and risk factors of occult OM and also evaluate the outcome of patients with and without such metastasis. Methods  This is a single institutional, retrospective study of patients with gastric cancer who underwent curative radical gastrectomy for a period of 3 years (April 1, 2016, to March 31, 2019). A complete omentectomy was performed in all patients and the omentum and nodal stations were dissected in the resected specimen and sent for pathological analysis. Clinical and epidemiological data were collected from the hospital patient database and analysis was done. Results  A total of 185 patients have been included in the study, with a mean age of 53.84 years. Twenty of the 185 patients had OM (10.8%). Age, sex, location of the tumor, and neoadjuvant chemotherapy were not statistically significant in predicting OM. However, tumor size and tumor depth were found to have a significant association with OM. The occurrence of OM was more likely to be associated with disease recurrence, especially in the peritoneum. The mean overall survival was 38.15 months (±3.33 SD), whereas patients with OM had lower survival, 23.31 months (±7.79 SD), with a p -value of 0.012. Conclusion  OM was not encountered in T1 and T2 gastric cancers and the incidence of OM in T3 and T4 tumors was approximately 12.7%. Therefore, complete omentectomy may be omitted in early T1/T2 tumors. OM was associated with poor prognosis, increased peritoneal recurrence, and decreased overall survival, in spite of a complete omentectomy, and may serve as a prognostic indicator for disease recurrence and overall survival.

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.