Gastrectomy with or without omentectomy for cT3–4 gastric cancer: a multicentre cohort study

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.

Comparison of the survival outcomes between retrocolic and antecolic Roux-en-Y reconstruction after gastrectomy for gastric cancer

Background

There are two methods of Roux-en-Y (RY) reconstruction after gastrectomy: the antecolic route (ACR) and retrocolic route (RCR). There is no evidence to support that the ACR achieves comparable long-term survival.

Methods

This was a multi-center historical cohort study. Patients diagnosed with clinical T3/4a and any N stage who underwent open gastrectomy and R0 resection for gastric adenocarcinoma between January 2006 and December 2012 were enrolled. The primary outcome was the hazard ratio of ACR for overall survival, with adjustment for confounding factors by propensity score matching, and a Cox proportional hazards model.

Results

A total of 1758 eligible patients were identified from the database. After matching, 410 patients in the ACR and RCR groups were included in the final analysis. The adjusted hazard ratio (95% CI) for ACR was 1.148 (0.870-1.492). The five-year survival rates in the ACR and RCR groups were 74.3% (69.5-78.4) and 77.3% (72.3-81.2), respectively. The short-term surgical outcomes of the two groups did not differ to a statistically significant extent.

Conclusion

The route used to lift the jejunum in RY reconstruction did not affect the incidence of long-term survival or postoperative complications. The ACR and RCR are both acceptable options for RY reconstruction during gastric cancer surgery.

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.

Conversion surgery after successful response to chemotherapy (S-1 + oxaliplatin + nivolumab) in a patient with stage IV gastric cancer with peritoneal metastasis (P1, CY1): a case report

We here present a case report of a patient with Stage IV gastric cancer with peritoneal metastasis (P1, CY1) who underwent conversion surgery after a successful response to chemotherapy (S-1 + oxaliplatin + nivolumab). The patient was a woman in her 60 s. Her chief complaint was epigastric pain. Upper gastrointestinal endoscopy showed Type 4 advanced carcinoma on the lesser curvature of the gastric body. Biopsy showed Group 5 (poorly differentiated adenocarcinoma) and HER2 was negative. Staging laparoscopy revealed seeding in the round ligament of the liver (P1) and adenocarcinoma cells in ascites (CY1). Ten courses of chemotherapy (S-1 + oxaliplatin + nivolumab) were administered, after which contrast-enhanced computed tomography showed that the primary tumor had shrunk and seeding was no longer detectable. Upper gastrointestinal endoscopy revealed scar-like changes. A second staging laparoscopy revealed that ascites cytology was negative and a biopsy of the round ligament of the liver showed no malignant cells (P0, CY0). Conversion surgery comprising laparoscopic total gastrectomy with D2 lymph node dissection and resection of the round ligament of the liver was performed. The postoperative course was uneventful. Histopathological examination of the resected specimen revealed no tumor cells in the gastric mesentery or the round ligament of the liver. The pathological diagnosis was gastric cancer [M, U, L, Less, Ant, Post, type4, T3(SS), N0, M0 (H0, P0, CY0), ypStage IIA]. Adjuvant chemotherapy (S-1) was commenced. The patient is still alive 7 months later with no evidence of recurrence.

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.

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.

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.

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.

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.

Partial omentectomy maybe practicable for T3 or shallower gastric cancer patients

BACKGROUND

Total omentectomy is often performed with gastrectomy as radical surgery for gastric cancer (GC) patients. However, it remains controversial whether GC patients can benefit from omentectomy. The aim of this study was to analyze the incidence and clinical significance of tumor deposits (TDs) in different anatomical subregions of perigastric omentum in GC patients undergoing gastrectomy with total omentectomy.

METHODS

From October 2011 to December 2013, 1253 patients who underwent gastrectomy with total omentectomy for GC were retrospective reviewed. The TDs in different anatomical subregions of perigastric omentum were examined.

RESULTS

Of 1253 patients, TDs positivity was 11.2%. Tumor deposits in the omentum of greater curvature and in the omentum of lesser curvature were associated with lymphovascular invasion, perineural invasion, advanced tumor node metastasis stages, and unfavorable survival. Besides, TDs in the proximal omentum of greater curvature and in the omentum of lesser curvature correlated with older patients and larger tumors. Kaplan-Meier curves showed that patients with TDs had worser overall survival (OS) than those without, regardless of TD positions. Patients with TDs in the omentum of greater curvature had the worst prognosis, followed by patients with TDs in the omentum of lesser curvature and patients with no TDs. Tumor deposits in the proximal omentum of greater curvature was an independent prognostic factor for OS. Moreover, only patients classified as pT4 had TDs in the distal omentum of greater curvature.

CONCLUSIONS

Patients with TDs in the omentum of greater curvature had the worst prognosis, followed by patients with TDs in the omentum of lesser curvature and patients with no TDs. In addition, partial omentectomy might be practicable for gastric cancer patients classified as T3 or shallower tumors.

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.

Complete Mesogastric Excisions Involving Anatomically Based Concepts and Embryological-Based Surgeries: Current Knowledge and Future Challenges

Surgeries for gastrointestinal tract malignancies are based on the paradigm that we should remove the tumour together with its lymphatic drainage in one block. This concept was initially proposed in rectal surgery and called a total mesorectal excision. This procedure gained much interest and has improved oncological results in rectal cancer surgery. The same idea for mesogastric and complete mesogastric excisions was proposed but, because of the complexity of the gastric mesentery, it has not become a standard technique. In this review, we analysed anatomical and embryological factors, proposed technical aspects of this operation and incorporated the available initial results of this concept. We also discussed analogies to other gastrointestinal organs, as well as challenges to this concept.

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.

Favorable Outcomes of Neoadjuvant Chemotherapy and Limited Para-Aortic Lymph Node Dissection for Advanced Gastric Cancer with Para-aortic Lymph Node Metastasis

BACKGROUND

Although para-aortic lymph node (PALN) metastasis from gastric cancer is a non-curative lesion, gastrectomy with complete PALN dissection (PAND) following neoadjuvant chemotherapy (NAC) is a tentative standard treatment in Japan, based on the results of a small-scale phase II clinical trial. However, whether complete PAND (C-PAND) is always necessary for such diseases is open to debate.

METHODS

Patients who received NAC followed by R0 gastrectomy for gastric cancer with clinical PALN metastasis at the Cancer Institute Hospital in Tokyo from 2005 to 2017 were reviewed in the present study. We assessed surgical findings and long-term outcomes.

RESULTS

In total, 44 patients receiving gastrectomy with C-PAND (n = 22) or limited PAND (L-PAND; n = 22) were included. Operation time was significantly longer in the C-PAND than in the L-PAND groups (363 min vs. 271 min, P = 0.037). There was no difference between the two groups in the ypStage classification and pattern of recurrence. The 5-year overall survival (OS) and relapse-free survival (RFS) curves were higher in the L-PAND group than the C-PAND group, without reaching a significant difference. The 5-year OS (42.9% vs. 75.7%, p = 0.017) and RFS (14.3% vs. 48.6%, p = 0.002) were significantly worse in the group of three or more, than in the group of less than three pathological PALN metastasis, whereas increasing numbers of harvested PALN were not associated with improved survival.

CONCLUSIONS

Curative gastrectomy with L-PAND following NAC for gastric cancer involving PALN may be an alternative treatment to C-PAND.

Omentectomy Does Not Affect the Postoperative Outcome of Patients With Locally Advanced Gastric Cancer: A Systematic Review and Meta-Analysis

OBJECTIVE

To explore the influence of omentectomy on postoperative outcomes in patients with locally advanced gastric cancer (LAGC).

BACKGROUND

Although several meta-analyses have investigated the influence of bursectomy on postoperative outcomes in patients with LAGC, no meta-analyses have explored the influence of omentectomy on postoperative outcomes in such patients.

METHODS

We performed a comprehensive electronic search of the literature up to December 2020 to identify studies that compared postoperative outcomes between patients with LAGC who did and did not undergo omentectomy. A meta-analysis was performed using random-effects models to calculate the risk ratio (RR) and 95% confidence interval (CI), and heterogeneity was analyzed using I² statistics.

RESULTS

Eight retrospective studies involving a total of 2658 patients with LAGC who underwent surgery were included in this meta-analysis. Among them, 3 propensity score matching (PSM) studies demonstrated that the 5-y recurrence-free survival (RFS) rate was 72.9% (314/431) in patients with LAGC who did not undergo omentectomy, whereas it was 70.3% (303/431) in those who did. The results revealed no significant difference in 5-y RFS between groups (RR, 0.91; 95% CI, 0.74-1.13; P = 0.41; I² = 0%). Two PSM studies also revealed no significant difference in 5-y overall survival (OS) between groups (RR, 0.77; 95% CI, 0.52-1.13; P = 0.18; I² = 47%).

CONCLUSIONS

The results of these meta-analyses show that omentectomy had no significant influence on 5-y OS, especially 5-y RFS, in patients with LAGC.

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

BACKGROUND

Omentectomy is considered an essential part of curative gastrectomy for locally advanced gastric cancer (GC), albeit without solid evidence. We conducted a randomized phase II trial (the TOP-G trial) comparing omentectomy and omentum preservation for gastric cancer. This report describes the short-term findings regarding the trial's secondary endpoints.

METHODS

The trial protocol was submitted to the University Hospital Medical Information Network Clinical Trials Registry ( http://www.umin.ac.jp/ctr/ : UMIN000005421). The key eligibility criteria were histologically confirmed cT2-4a and N0-2 gastric adenocarcinoma. Short-term surgical outcomes, including morbidity and mortality, were compared between the omentectomy group (group A, control arm) and the omentum-preserving surgery group (group B, test arm). All procedures were performed via an open approach. Based on a non-inferiority margin of 7%, statistical power of 0.7, and type I error of 0.2, the sample size was set to 250 patients.

RESULTS

A total of 251 patients were eligible and randomized (group A: 125 patients, group B: 126 patients) between April 2011 and October 2018. After excluding patients who had peritoneal metastasis or laparotomy history, safety outcomes were analyzed for 247 patients. Group A had a significantly longer median operation time (225 min vs. 204 min, p = 0.022) and tended to have greater median blood loss (260 mL vs. 210 mL p = 0.073). The incidences of morbidity were similar and < 10% in both groups (8% vs. 9%, p = 1.000). There was no mortality in either group.

CONCLUSIONS

Operative risk was generally similar between omentectomy and omentum-preserving surgery for locally advanced gastric cancer.