Immunohistochemical Markers of the Epithelial-to-Mesenchymal Transition (EMT) Are Related to Extensive Lymph Nodal Spread, Peritoneal Dissemination, and Poor Prognosis in the Microsatellite-Stable Diffuse Histotype of Gastric Cancer

Cell Biology of Cancer Peritoneal Metastasis: Multiclonal Seeding and Peritoneal Tumor Microenvironment

Peritoneal metastasis, also known as peritoneal dissemination or carcinomatosis, refers to the spread of cancer to the peritoneum that lines the abdominal and pelvic cavities and covers the abdominal organs. Peritoneal metastasis typically occurs in advanced cancers of abdominal origin, most commonly gastrointestinal and gynecological cancers. Conventional chemotherapy has limited efficacy, and no effective molecular-targeted therapy is currently available for peritoneal metastasis. As a result, peritoneal metastasis is associated with poor outcomes and significantly reduced quality of life in patients with advanced cancers. This is largely due to a limited understanding of the molecular and cellular mechanisms underlying peritoneal metastasis. However, recent studies employing innovative approaches have provided novel insights into the mechanisms of peritoneal metastasis, contributing to the development of novel therapeutic strategies. In this review, we summarize recent findings on the cell biological aspects of peritoneal metastasis and potential therapeutic target molecules. In particular, we emphasize the importance of cancer cell clustering within the abdominal cavity, which drives multiclonal peritoneal seeding. We also focus on the interactions of cancer cells with mesothelial cells and cancer-associated fibroblasts within the peritoneal tumor microenvironment.

Clinical implications of epithelial-to-mesenchymal transition in cancers which potentially spread to peritoneum

Epithelial-to-mesenchymal transition (EMT) is a biological process by which epithelial cells increase their motility and acquire invasive capacity. It represents a crucial driver of cancer metastasis and peritoneal dissemination. EMT plasticity, with cells exhibiting hybrid epithelial/mesenchymal states, and its reverse process, mesenchymal-to-epithelial transition (MET), allows them to adapt to different microenvironments and evade therapeutic intervention. Resistance to conventional treatments, including chemotherapy, is a major problem. Therapies targeting EMT may inhibit tumour cell migration and invasion, while affecting normal cells and repair mechanisms, resulting in potential side effects. This paper addresses the question of the impact of EMT status on cancers with potential spread to the peritoneum, which has remained unclear in literature. Relevant studies were selected from 2000 to 2024. Three macrosections were analysed: (i) pathological characteristics, (ii) surgical implications and (iii) oncological therapies. The focus was on survival and peritoneal recurrence time in patients who underwent surgical treatment.

Clinical calculator based on CT and clinicopathologic characteristics predicts short-term prognosis following resection of microsatellite-stabilized diffuse gastric cancer

PURPOSE

Although microsatellite stability/Epithelial-mesenchymal transition (MSS/EMT) subtypes have been reported in multiple cancer prognosis studies, strong confounding factors between MSS/EMT (usually with Lauren's diffuse phenotype) and diffuse gastric cancer (GC) may obscure the independent prognostic value of diffuse GC. Additionally, recent studies suggest a strong correlation between mural stratification based on CT and diffuse GC. This study aims to investigate potential prognostic factors of MSS diffuse GC using mural stratification and to develop a risk assessment model.

METHODS

This retrospective study included 131 patients with MSS diffuse GC who underwent radical surgery. Univariate and multivariate Cox proportional hazards regression analysis was used to identify model predictors and construct a nomogram for overall survival (OS) and recurrence-free survival (RFS) risks. The model's performance was evaluated using ROC, accuracy, and C-index. Internal validation of the model was conducted using the bootstrap resampling method.

RESULTS

Among 131 cases, 60 cases (45.8%) exhibited grade 2 mural stratification, which correlated with a poorer tumor prognosis and a more invasive phenotype. Furthermore, a nomogram for predicting OS and RFS prognosis was established based on multivariate results (age, extranodal invasion, mural stratification, and/or P53). The nomogram demonstrated excellent performance, with an AUC of 0.859 (95% CI 0.794-0.924) for OS and 0.859 (95% CI 0.789-0.929) for RFS. Internal validation using 1000 bootstrap samples yielded AUC values of 0.845 and 0.846 for OS and RFS, respectively.

CONCLUSION

Grade 2 mural stratification based on CT imaging revealed a more aggressive invasive phenotype, characterized by increased LN metastasis, higher rates of peritoneal metastasis, and a poorer short-term prognosis. Furthermore, the CT phenotype-based nomogram demonstrates favorable discrimination and calibration, enabling convenient individual short-term prognostic evaluation following resection of MSS diffuse GC.

Challenging the Dogma: Stage migration or negative lymph nodes, which of them is the main player on gastric cancer prognosis?

Expanding loco-regional nodes harvesting is expected to increase survival. This improvement may be associated to stage migration (SM). However, the great bulk of harvested lymph nodes observed in large dissections is negative. M&M: 830 patients who received R0 gastrectomy for adenocarcinoma were included. pN+ patients with <26 nodes (n = 209) were included for a simulation to "offer 26 nodes" - SM (proportional and exponential based) was simulated and analysed through machine learning algorithms. Overall Survival (OS), in native and simulated stages, were compared. OS of extended lymphadenectomies (pN+, D ≥ 26, n = 273) was compared with the simulated curves. OS of patients in the following dissection intervals of negative nodes were compared: <16 (n = 233), 16-25 (n = 258), ≥26 (n = 339). RESULTS: After simulation to 26 nodes (pN+, D < 26 patients, n = 209), staging was recomputed. OS of native vs simulated early-stages (I-II) and advanced stages (III) were not different (p > 0.05). OS of patients with lymphadenectomy (≥26) was better than simulated for early and advanced stages (p = 0.008; p = 0.005). OS of patients included in distinct intervals of negative lymph nodes were different (p < 0.001). These intervals were an independent prognostic factor (multivariate analysis). CONCLUSIONS: The influence of Stage Migration was null in this set of simulations and Will Rogers phenomenon was not observed. Extended dissection performed better in OS. But the influence of the number of negative nodes, even in large dissections, was highlighted. By emphasizing the role of negative nodes, we aim to facilitate more informed decision-making in management of gastric cancer patients, ultimately leading to improved treatment outcomes and patient care.

Posterior and Para-Aortic (D2plus) Lymphadenectomy after Neoadjuvant/Conversion Therapy for Locally Advanced/Oligometastatic Gastric Cancer

Super-extended (D2plus) lymphadenectomy after chemotherapy has been reported in only a few studies. This retrospective study evaluates survival outcomes in a Western cohort of locally advanced or oligometastatic gastric cancer patients who underwent D2plus lymphadenectomy after neoadjuvant chemotherapy. A total of 97 patients treated between 2010 and 2022 were included. Of these, 62 had clinical stage II/III disease, and 35 had stage IV disease. Most patients (65%) received preoperative DOC/FLOT chemotherapy. The mean number of lymph nodes harvested was 39. Pathological positive nodes in the posterior/para-aortic stations occurred in 17 (17.5%) patients. Lymphovascular invasion, ypN stage, clinical stage, and perineural invasion were predictive factors for positive posterior/para-aortic nodes. Postoperative complications occurred in 21 patients, whereas severe complications (grade III or more) occurred in 9 cases (9.3%). Mortality rate was 1%. Median overall survival (OS) was 59 months (95% CI: 13-106), with a five-year survival rate of 49 ± 6%; the five-year OS after R0 surgery was 60 ± 7%. In patients with positive posterior/para-aortic nodes, the median OS was 15 months (95% CI: 13-18). D2plus lymphadenectomy after chemotherapy for locally advanced or oligometastatic gastric cancer is feasible and associated with low morbidity/mortality rates. The incidence of pathological metastases in posterior/para-aortic nodes is not negligible even after systemic chemotherapy, with poor long-term survival.

EZH2: An Accomplice of Gastric Cancer

Gastric cancer is the fifth most common cancer and the third leading cause of cancer deaths worldwide. Understanding the factors influencing the therapeutic effects in gastric cancer patients and the molecular mechanism behind gastric cancer is still facing challenges. In addition to genetic alterations and environmental factors, it has been demonstrated that epigenetic mechanisms can also induce the occurrence and progression of gastric cancer. Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of the polycomb repressor complex 2 (PRC2), which trimethylates histone 3 at Lys-27 and regulates the expression of downstream target genes through epigenetic mechanisms. It has been found that EZH2 is overexpressed in the stomach, which promotes the progression of gastric cancer through multiple pathways. In addition, targeted inhibition of EZH2 expression can effectively delay the progression of gastric cancer and improve its resistance to chemotherapeutic agents. Given the many effects of EZH2 in gastric cancer, there are no studies to comprehensively describe this mechanism. Therefore, in this review, we first introduce EZH2 and clarify the mechanisms of abnormal expression of EZH2 in cancer. Secondly, we summarize the role of EZH2 in gastric cancer, which includes the association of the EZH2 gene with genetic susceptibility to GC, the correlation of the EZH2 gene with gastric carcinogenesis and invasive metastasis, the resistance to chemotherapeutic drugs of gastric cancer mediated by EZH2 and the high expression of EZH2 leading to poor prognosis of gastric cancer patients. Finally, we also clarify some of the current statuses of drug development regarding targeted inhibition of EZH2/PRC2 activity.

Extended Lymphadenectomy for Gastric Cancer in the Neoadjuvant Era: Current Status, Clinical Implications and Contentious Issues

Despite its decreasing incidence, gastric cancer remains an important global healthcare problem due to its overall high prevalence and high mortality rate. Since the MAGIC and FNLCC/FFCD trials, the neoadjuvant chemotherapy has been recommended throughout Europe in gastric cancer. Potential benefits of preoperative treatments include a higher rate of R0 resection achieved by downstaging the primary tumor, a likely effect on micrometastases and isolated tumor cells in the lymph nodes, and, as a result, improved cancer-related survival. Nevertheless, distortion of anatomical planes of dissection, interstitial fibrosis, and sclerotic tissue changes may increase surgical difficulty. The collection of at least twenty-five lymph nodes after neoadjuvant therapy would seem to ensure removal of undetectable node metastasis and reduce the likelihood of locoregional recurrence. It is not what you take but what you leave behind that defines survival. Therefore, para-aortic lymph node dissection is safe and effective after neoadjuvant chemotherapy, in both therapeutic and prophylactic settings. In this review, the efficacy of adequate lymph node dissection, also in a neoadjuvant setting, has been investigated in the key studies conducted to date on the topic.