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

Korean Practice Guidelines for Gastric Cancer 2024: An Evidence-based, Multidisciplinary Approach (Update of 2022 Guideline)

Gastric cancer is one of the most common cancers in both Korea and worldwide. Since 2004, the Korean Practice Guidelines for Gastric Cancer have been regularly updated, with the 4th edition published in 2022. The 4th edition was the result of a collaborative work by an interdisciplinary team, including experts in gastric surgery, gastroenterology, endoscopy, medical oncology, abdominal radiology, pathology, nuclear medicine, radiation oncology, and guideline development methodology. The current guideline is the 5th version, an updated version of the 4th edition. In this guideline, 6 key questions (KQs) were updated or proposed after a collaborative review by the working group, and 7 statements were developed, or revised, or discussed based on a systematic review using the MEDLINE, Embase, Cochrane Library, and KoreaMed database. Over the past 2 years, there have been significant changes in systemic treatment, leading to major updates and revisions focused on this area. Additionally, minor modifications have been made in other sections, incorporating recent research findings. The level of evidence and grading of recommendations were categorized according to the Grading of Recommendations, Assessment, Development and Evaluation system. Key factors for recommendation included the level of evidence, benefit, harm, and clinical applicability. The working group reviewed and discussed the recommendations to reach a consensus. The structure of this guideline remains similar to the 2022 version. Earlier sections cover general considerations, such as screening, diagnosis, and staging of endoscopy, pathology, radiology, and nuclear medicine. In the latter sections, statements are provided for each KQ based on clinical evidence, with flowcharts supporting these statements through meta-analysis and references. This multidisciplinary, evidence-based gastric cancer guideline aims to support clinicians in providing optimal care for gastric cancer patients.

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.

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.

Machine learning models for predicting one-year survival in patients with metastatic gastric cancer who experienced upfront radical gastrectomy

Tumor metastasis is a common event in patients with gastric cancer (GC) who previously underwent curative gastrectomy. It is meaningful to employ high-volume clinical data for predicting the survival of metastatic GC patients. We aim to establish an improved machine learning (ML) classifier for predicting if a patient with metastatic GC would die within 12 months. Eligible patients were enrolled from a Chinese GC cohort, and the complete detailed information from medical records was extracted to generate a high-dimensional dataset. Appropriate feature engineering and feature filter were conducted before modeling with eight algorithms. A 10-fold cross validation (CV) nested in a holdout CV (8:2) was employed for hyperparameter tuning and model evaluation. Model selection was based on the area under the receiver operating characteristic (AUROC) curve, recall, and precision. The selected model was globally explained using interpretable surrogate models. Of the total 399 cases (median survival of 8.2 months), 242 patients survived less than 12 months. The linear discriminant analysis (LDA), support vector machine (SVM), and random forest (RF) model had the highest AUROC (0.78 ± 0.021), recall (0.93 ± 0.031), and precision (0.80 ± 0.026), respectively. The LDA model created a new function that generally separated the two classes. The predicted probability of the SVM model was interpreted using a linear regression model visualized by a nomogram. The predicted class of the RF model was explained using a decision tree model. In summary, analyzing high-volume medical data by ML is helpful to produce an improved model for predicting the survival in patients with metastatic GC. The algorithm should be carefully selected in different practical scenarios.

Diagnostic Value of CT Window Technique for Primary Omentum Infarction

Objective

The diagnostic value of CT window width technique in primary omentum infarction was evaluated by this study.

Methods

The abdominal CT data of 32 patients with clinically diagnosed abdominal omentum infarction were retrospectively selected and analyzed. The fixed window position was 50 HU, and the window width was 135 HU, 250 HU (abdomen), 350 HU (mediastinum), and 500 HU, respectively. The detection rate of lesions was analyzed and compared.

Results

Window widths of 135 HU, 250 HU (abdomen), 350 HU (mediastinum), and 500 HU have a detection rate of 12.5% (4 cases), 62.5% (20 cases), 100% (32 cases), 100% (32 cases) for abdominal omental lesions, respectively. However, 500 HU showed worse abdominal bowel and parenchymal organs than 350 HU.

Conclusion

According to the comprehensive image quality, the ideal window width for diagnosis of primary omentum infarction is 350HU (mediastinal) window width.

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.

Comparison of postoperative pancreatic fistula between open and laparoscopic surgery in patients with gastric cancer: A meta-analysis

Background

Open gastrectomy"OG" compared with laparoscopic gastrectomy"LG" in patients with gastric cancer"GC" has been widely discussed over the past years. However, the lack of comparative analysis in postoperative pancreatic fistula "POPF" hinders its severity as surgical procedures developed rapidly. Therefore, there are still moot on whether one of these surgical options is superior in POPF.

Objective

To compare the incidence of POPF in patients undergoing OG and LG for gastric cancer "GC".

Methods

Articles from January 2011 to August 2021 that compared LG and OG for GC were reviewed. Cohort studies were included in our study. The quality of enrolled studies was evaluated. Outcomes regarding POPF complication and relative operation results were analyzed. Statistical analysis portrayed the Weighted mean difference"WMD"and the odds ratio"OR"with a 95% confidence interval "CI". The curative effect was analyzed using RevMan 5.4.1 software.

Results

Totally 7 articles met the inclusion criteria, including 3194 patients with treatment of gastrectomy surgeries for gastric cancer "GC". There was no significant difference observed in POPF incidence (OR, 95% CI = 1.04 [0.74,1.46], P = 0.81) between OG group and LG group in patients undergoing GC gastrectomy.

Conclusion

We stringently explored the current incidence of POPF after GC gastrectomy, comparing its incidence during LG and OG, there was no significant difference between OG and LG in the incidence of POPF, and surgeons should give more concern for improvement in surgical techniques. Further research is still needed to explore the risk of causes and surgical techniques should be considered cautiously in a clinical procedure.