Review and Update on the Role of Peritoneal Cytology in the Treatment of Gastric Cancer

Tumor-positive peritoneal cytology in patients with gastric cancer is associated with poor outcome: A nationwide study

BACKGROUND

The clinical significance of tumor-positive peritoneal cytology (CYT+) in gastric cancer (GC) patients is unclear. This nationwide cohort study aimed to i) assess the frequency of cytological analysis at staging laparoscopy; ii) determine the prevalence of CYT+GC; and iii) compare overall survival (OS) in CYT+ patients versus those with (PM+) and those without (PM-) macroscopic peritoneal disease.

METHODS

All patients diagnosed with cT1-4, cN0-2 and M0 or synchronous PM GC between 2016-2021 were identified in the Netherlands Cancer Registry database and linked to the nationwide pathology database.

RESULTS

A total of 4397 patients was included, of which 40 % underwent cytological assessment following staging laparoscopy (863/1745). The prevalence of CYT+ was 8 %. A total of 69 patients had CYT+(1.6 %), 789 (17.9 %) had PM+ and 3539 (80.5 %) had PM- disease. Hazard ratio for OS in CYT+ versus PM+ was 0.86 (95 %CI 0.64-1.17, p-value=0.338), and in PM- versus PM+0.43 (95 %CI 0.38-0.49, p-value<0.001). No survival difference was found between systemic chemotherapy versus surgical resection in CYT+ patients.

DISCUSSION

In this nationwide study, OS for gastric cancer patients with CYT+ was equally unfavorable as for those with PM+ and significantly worse as compared to those with PM-. The optimal treatment strategy has yet to be established.

OLIGOMETASTASIS IN GASTRIC CANCER TREATMENT: IS THERE A PLACE FOR THE SURGEON?

Metastatic gastric cancer traditionally hinders surgical treatment options, confining them to palliative procedures. The presence of metastases in these tumors is classified as M1, irrespective of their characteristics, quantity, or location. However, oligometastatic disease emerged as an intermediate state between localized and widely disseminated cancer. It exhibits diverse patterns based on metastatic disease extent, type, and location. Adequately addressing this distinctive metastatic state necessitates tailored strategies that surpass the realm of palliative care. Differentprimary tumor types present discernible scenarios of oligometastatic disease, including preferred sites of occurrence and chronological progression. Due to the novelty of this theme and the heterogeneity of the disease, uncertainties still exist, and the ability to provide confident guidelines is challenging. Currently, there are no effective predictors to determine the response and provide clear indications for surgical interventions and systemic treatments in oligometastatic disease. Treatment decisions are commonly based on apparent disease control by systemic therapies, with a short observation period and imaging assessments. Nonetheless, the inherent risk of misinterpretation remains a constant concern. The emergence of novel technologies and therapeutic modalities, such as immunotherapy, cellular therapy, and adoptive therapies, holds the potential to reshape the landscape of surgical treatment for the oligometastatic disease in gastric cancer, expanding the surgeon's role in this multidisciplinary approach. Prospective tools for patient selection in oligometastatic gastric cancer are being explored. Using non-invasive, cost-effective, widely available imaging techniques that provide real-time information may revolutionize medical practice, ensuring precision medicine accessibility, even in resource-constrained small healthcare facilities. Incorporating molecular classifications, liquid biopsies, and radiomic analysis in a complementary protocol will augment patient selection precision for surgical intervention in oligometastasis. Hopefully, these advancements will render surgeries unnecessary in many cases by providing highly effective alternative treatments.

Efficacy of chemotherapy versus surgery as initial treatment for gastric cancer with positive peritoneal cytology

BACKGROUND

The prognosis of gastric cancer (GC) patients with positive peritoneal cytology (CY1) without other distant metastasis is poor, and there are no standard treatment strategies. Our study aimed to compare the survival outcomes of CY1 GC patients receiving chemotherapy or surgery as initial treatment.

METHODS

From February 2017 to January 2020, clinical and pathological data of patients diagnosed with CY1 GC without other distant metastasis in the Peking University Cancer Hospital was reviewed. Patients were divided into two groups: chemotherapy-initial group and surgery-initial group. In chemotherapy-initial group, patients received preoperative chemotherapy initially. According to the treatment response, the patients were divided into three subgroups: conversion gastrectomy group, palliative gastrectomy group, and further systematic chemotherapy group. In surgery-initial group, patients underwent gastrectomy followed by postoperative chemotherapy.

RESULTS

A total of 96 CY1 GC patients were included with 48 patients in each group. In chemotherapy-initial group, preoperative chemotherapy yielded an objective response rate of 20.8% and disease control rate of 87.5%. Conversion to CY0 after preoperative chemotherapy was obtained in 24 (50%) patients. The median overall survival was 36.1 months in chemotherapy-initial group and 29.7 months in surgery-initial group (p = 0.367). The median progression-free survival was 18.1 months in chemotherapy-initial group and 16.1 months in surgery-initial group (p = 0.861). The 3-year overall survival rates were 50.0% and 47.9%, respectively. In chemotherapy-initial group, twenty-four patients who converted to CY0 by preoperative chemotherapy and received surgery obtained a significantly better prognosis. The median overall survival was still not reached in these patients.

CONCLUSION

There was no significant difference in survival outcomes between chemotherapy-initial group and surgery-initial group. CY1 GC patients who converted to CY0 by preoperative chemotherapy and received radical surgery could obtain a favorable long-term prognosis. Further investigation should focus on preoperative chemotherapy to eliminate peritoneal cancer cell.

TRIAL REGISTRATION

This study is retrospectively registered.

N6-methyladenosine (m6A) reader IGF2BP2 promotes gastric cancer progression via targeting SIRT1

N⁶-methyladenosine (m⁶A) modification acts as the most prevalent internal modification in eukaryotic mRNA. Emerging evidence shows the critical biological roles of m⁶A key enzymes in human cancers. However, the roles of m⁶A binding protein IGF2BP2 in gastric cancer (GC) progression are still unclear. In this study, we confirmed that IGF2BP2 was highly expressed in GC cell lines and tumor tissues. Knocking down of IGF2BP2 suppressed cell proliferation and migration, and repressed xenograft tumor growth in vivo, while IGF2BP2 overexpression promoted the proliferation and migration. Mechanistically, we identified that IGF2BP2 regulated GC the proliferation/migration through recognizing the m⁶A modification sites of SIRT1 mRNA. In general, our findings demonstrated a novel regulatory mechanism that IGF2BP2/SIRT1 axis modulated GC progression in an m⁶A-dependent manner, suggesting that m⁶A may be a therapeutic target for GC.

Development of the PERI-Gastric (PEritoneal Recurrence Index) and PERI-Gram (Peritoneal Recurrence Index NomoGRAM) for predicting the risk of metachronous peritoneal carcinomatosis after gastrectomy with curative intent for gastric cancer

BACKGROUND

A model that quantifies the risk of peritoneal recurrence would be a useful tool for improving decision-making in patients undergoing curative-aim gastrectomy for gastric cancer (GC).

METHODS

Five Italian centers participated in this study. Two risk scores were created according to the two most widely used pathologic classifications of GC (the Lauren classification and the presence of signet-ring-cell features). The risk scores (the PERI-Gastric 1 and 2) were based on the results of multivariable logistic regressions and presented as nomograms (the PERI-Gram 1 and 2). Discrimination was assessed with the area under the curve (AUC) of receiver operating curves. Calibration graphs were constructed by plotting the actual versus the predicted rate of peritoneal recurrence. Internal validation was performed with a bootstrap resampling method (1000 iterations).

RESULTS

The models were developed based on a population of 645 patients (selected from 1580 patients treated from 1998 to 2018). In the PERI-Gastric 1, significant variables were linitis plastica, stump GC, pT3-4, pN2-3 and the Lauren diffuse histotype, while in the PERI-Gastric 2, significant variables were linitis plastica, stump GC, pT3-4, pN2-3 and the presence of signet-ring cells. The AUC was 0,828 (0.778-0.877) for the PERI-Gastric 1 and 0,805 (0.755-0.855) for the PERI-Gastric 2. After bootstrap resampling, the PERI-Gastric 1 had a mean AUC of 0.775 (0.721-0.830) and a 95%CI estimate for the calibration slope of 0.852-1.505 and the PERI-Gastric 2 a mean AUC of 0.749 (0.693-0.805) and a 95%CI estimate for the slope of 0.777-1.351. The models are available at www.perigastric.org .

CONCLUSIONS

We developed the PERI-Gastric and the PERI-Gram as instruments to determine the risk of peritoneal recurrence after curative-aim gastrectomy. These models could direct the administration of prophylactic intraperitoneal treatments.

Predictive Effect of Systemic Immune-Inflammation Index Combined With Prognostic Nutrition Index Score on Efficacy and Prognosis of Neoadjuvant Intraperitoneal and Systemic Paclitaxel Combined With Apatinib Conversion Therapy in Gastric Cancer Patients With Positive Peritoneal Lavage Cytology: A Prospective Study

Background

Gastric cancer with only peritoneal lavage cytology (GC-CY₁) is a special type of gastric cancer, which is defined as stage IV. The pre-treatment systemic immune-inflammation index (SII) and prognostic nutritional index (PNI) are representative blood indexes of systemic inflammatory response and nutritional status. However, the clinical significance of combined detection of these two indexes is still unclear. This study aims to evaluate the clinical value of the new score system by combining SII and PNI (SII-PNI score) as a predictor of efficacy and prognosis after neoadjuvant intraperitoneal and systemic (NIPS) paclitaxel combined with Apatinib conversion therapy for GC-CY₁ patients.

Methods

We registered a prospective clinical study involving 36 GC-CY₁ patients from April 2018 to August 2019 (NCT03718624). All patients underwent re-laparoscopic exploration after treatment. According to free cancer cells (FCCs) status, these patients were divided into FCCs group and non-FCCs group. The SII-PNI score ranged from 0 to 2 as follows: score of 2, high SII (≥512.1) and low PNI (≤52.9); score of 1, either high SII or low PNI; score of 0, no high SII nor low PNI.

Results

All patients underwent re-laparoscopic exploration after 3 cycles of NIPS paclitaxel and Apatinib conversion therapy. Among them, 28 cases (77.78%) were in non-FCCs group, and 8 cases (22.22%) were in FCCs group. The SII-PNI score of non-FCCs patients was significantly lower than that of FCCs patients (p=0.041). The prognosis of patients with high SII-PNI score was significantly worse than that of patients with low SII-PNI score (p<0.001). Multivariate analysis showed that SII-PNI score was an independent prognostic factor for predicting overall survival and progression-free survival (p=0.001, 0.002).

Conclusion

Pretreatment SII-PNI score is an important predictor for the efficacy of GC-CY₁ patients after NIPS paclitaxel combined with Apatinib conversion therapy, which can help to identify high-risk groups and predict prognosis.

Primary and metastatic peritoneal surface malignancies

Peritoneal surface malignancies comprise a heterogeneous group of primary tumours, including peritoneal mesothelioma, and peritoneal metastases of other tumours, including ovarian, gastric, colorectal, appendicular or pancreatic cancers. The pathophysiology of peritoneal malignancy is complex and not fully understood. The two main hypotheses are the transformation of mesothelial cells (peritoneal primary tumour) and shedding of cells from a primary tumour with implantation of cells in the peritoneal cavity (peritoneal metastasis). Diagnosis is challenging and often requires modern imaging and interventional techniques, including surgical exploration. In the past decade, new treatments and multimodal strategies helped to improve patient survival and quality of life and the premise that peritoneal malignancies are fatal diseases has been dismissed as management strategies, including complete cytoreductive surgery embedded in perioperative systemic chemotherapy, can provide cure in selected patients. Furthermore, intraperitoneal chemotherapy has become an important part of combination treatments. Improving locoregional treatment delivery to enhance penetration to tumour nodules and reduce systemic uptake is one of the most active research areas. The current main challenges involve not only offering the best treatment option and developing intraperitoneal therapies that are equivalent to current systemic therapies but also defining the optimal treatment sequence according to primary tumour, disease extent and patient preferences. New imaging modalities, less invasive surgery, nanomedicines and targeted therapies are the basis for a new era of intraperitoneal therapy and are beginning to show encouraging outcomes.

Molecular Cytology by One-Step Nucleic Acid Amplification (OSNA) Assay of Peritoneal Washings during D2 Gastrectomy in Advanced Gastric Cancer Patients: Preliminary Results

The presence of peritoneal free cancer cells (FCC) in gastric cancer (GC) patients is a poor prognostic factor. D2 gastrectomy may induce exfoliated FCC spread from the primary tumour or involved lymph nodes (LN). Conventional cytology for FCC detection has several limitations, whereas prophylactic use of extensive intraoperative peritoneal lavage (IPL) does not improve survival. A prospective single-arm observational study was conducted to verify whether D2 gastrectomy causes an intraoperative increase of FCC in peritoneal fluid. Twenty-seven GC patients underwent D2 gastrectomy, followed by objective quantitative measurements of CK19 mRNA level reflecting FCC with One-Step Nucleic Acid Amplification (OSNA) assay. The IPL with 3000 mL of saline was performed twice: (1) after gastrectomy with D2 lymphadenectomy and (2) after alimentary tract reconstruction. The IPL samples were analysed by initial cytology and four (1-4) consecutive OSNA assays. Initial OSNA measurement (1) revealed positive results (≥24.6 cCP/μL) in 7 (29.6%) patients. Subsequent OSNA measurements showed a significant decrease in the FCC level after D2 gastrectomy (1 vs. 2; p = 0.0012). The first IPL induced a non-significant increase in the FCCs (2 vs. 3, p = 0.3300), but the second IPL reversed it to normal levels (3 vs. 4, p = 0.0.0574). The OSNA assay indicates a temporal intraoperative increase in the peritoneal FCC in advanced GC patients undergoing D2 gastrectomy. Two consecutive IPLs are necessary to reverse the increase of CK19 mRNA level in peritoneal washings.

Extended intraoperative peritoneal lavage as prophylactic peritoneal recurrence for locally advanced gastric cancer: a prospective randomized trial

BACKGROUND

To demonstrate whether extensive intraoperative peritoneal lavage (EIPL) could yield better results in overall survival and less recurrence, regardless of peritoneal cytology, compared to standard peritoneal lavage (SPL).

METHODS

A prospective randomised multicenter study including 94 patients (47 per arm) to detect a 20% difference in 3-year overall survival in patients with locally advanced tumours without peritoneal carcinomatosis. Three samples of peritoneal fluid were obtained (at the beginning, the end of procedure and after the assigned peritoneal lavage). Clinicopathological and surgical data were analysed by group. Postoperative complications, location of recurrence and surgical approach were evaluated. Overall survival was calculated by the Kaplan-Meier method and the uni/multivariate analysis for prognostic factors was carried out using Cox regression analysis.

RESULTS

A total of 86 patients were analysed (4 excluded per group). No statistical differences were observed in clinicopathological or surgical data between groups, considering both groups well-balanced for analysis. Overall survival at 3 years was 64.3% for SPL vs. 62.3% for EIPL (p 0.421). Only three patients had at least one positive peritoneal cytology (1:2). There were no differences regarding postoperative complications (SPL: 37.2% vs. EIPL: 32.5%, p 0.65) or between location of recurrence and number of recurrences. The number of recurrences did not differ between surgical approaches, but locoregional and peritoneal recurrences were fewer with the laparoscopic approach (p 0.048).

CONCLUSIONS

The regular use of extensive peritoneal lavage in patients with locally advanced gastric cancer, regardless of peritoneal cytology, has not been effective as prophylaxis of peritoneal recurrence or better survival.

Rapid Detection of Free Cancer Cells in Intraoperative Peritoneal Lavage Using One-Step Nucleic Acid Amplification (OSNA) in Gastric Cancer Patients

Cytokeratin-19 (CK19) has been proven to be commonly expressed by cancer cells in a variety of solid tumors and may serve as a suitable marker of metastases in gastric cancer (GC). Since objective assessment of peritoneal lavage or fluid for free cancer cells (FCC) is essential for clinical decision making in patients with GC, it is important to develop a quantitative and reproducible method for such evaluation. We assessed the possible application of One-Step Nucleic Acid amplification (OSNA) assay as a rapid method for FCC detection in intraoperative peritoneal lavage or fluid of GC patients. Seventy-eight intraoperative peritoneal lavage or fluid samples were eligible for the analysis by conventional cytology and OSNA examination. The concentration of CK19 mRNA in intraoperative peritoneal lavage and fluid was compared with the conventional cytological assessment. CK19 mRNA concentration was detected by OSNA assay. For peritoneal lavage samples, sensitivity and specificity were 83.3% and 87.8%, respectively. In peritoneal fluid, significantly higher CK19 values were observed in patients with serosal infiltration (medians: 100 copies/µL vs. 415.7 copies/µL; p = 0.0335) and lymph node metastases (medians: 2.48 copies/µL vs. 334.8 copies/µL). OSNA assay turns out to be an objective, fast, and reproducible quantitative method of FCC assessment.