Role of genetic detection in peritoneal washes with gastric carcinoma: The past, present and future

Comparison of Peritoneal Cytology Results Before and After Resection in Gastric Cancer Patients

OBJECTIVE

Peritoneal cytology is used to detect the peritoneal spread of gastric cancer and to assess survival rate. The aim of this study was to compare the risk factors, recurrence, and survival of gastric cancer patients with positive and negative peritoneal cytology before and after resection.

MATERIALS AND METHODS

Patients with gastric cancer who underwent elective surgery were retrospectively analysed. The study covered a period between September 2018 and September 2020. After applying the exclusion criteria, 57 patients were included in the study. For the purpose of this study, peritoneal cytology was taken from the same three intra-abdominal regions before and after resection from patients with operable gastric cancer.

RESULTS

Of the 57 patients included in the study, 36 (63.2%) were male patients and 21 (36.8%) were female patients. Preoperative or postoperative malignant cytology was detected in 12 patients (21.1%). Tumour diameter was larger in patients with preoperatively detected malignant cytology than in the patients with postoperatively positive malignant cytology (66.67 mm vs. 44.44 mm) (p = 0.006). The recurrence rate was higher in patients with preoperative and postoperative positive cytology than in those with negative cytology (p = 0.019). The survival of patients with preoperative malignant cytology was worse than the survival of patients with preoperative benign cytology (p = 0.011). A significant correlation was found between lymphovascular invasion (+), perineural invasion (+), T4, Stage 3 disease, number of malignant lymph nodes, and preoperative cytology positivity (p <0.05).

CONCLUSION

In our study, we found that the preoperative cytology positivity is associated with lymphovascular invasion positivity, perineural invasion positivity, T4 tumour, Stage 3 disease, and the number of malignant lymph nodes. Postoperative positive cytology was not associated with the same variables. Because of the significant associations in preoperative positivity, fluid samples should be obtained immediately after the abdomen is open and before the tumour is manipulated. If possible, fluid samples should be taken from different quadrants, but if the sample is to be taken from a single quadrant, it should be taken from the pelvis.

Issues on peritoneal metastasis of gastric cancer: an update

BACKGROUND

Peritoneal metastasis (PM) is one of the most common forms of metastasis with a very poor prognosis in patients with gastric cancer (GC). The mechanisms, diagnosis, and management of PM remain controversial.

MAIN BODY

Stephen Paget's "seed-and-soil" hypothesis gives us an illustration of the mechanisms of PM. Recently, hematogenous metastasis and exosomes from GC are identified as novel mechanisms for PM. Diagnostic accuracy of conventional imaging modalities for PM is not satisfactory, but texture analysis may be a useful adjunct for the prediction of PM. Biological markers in peritoneal washings are helpful in identifying patients at high risk of PM, but many limitations remain to be overcome. Response of PM from systemic chemotherapy alone is very limited. However, conversion therapy is confirmed to be safe and able to prolong the survival of GC patients with PM. As an important part of conversion therapy, intraperitoneal chemotherapy with taxanes has become an ideal approach with several advantages. Additionally, gastrectomy should be considered in patients who would tolerate surgery if a remarkable response to chemotherapy was observed.

CONCLUSION

Texture analysis is a reliable adjunct for the prediction of PM, and conversion therapy provides a new choice for GC patients with PM. The underlying mechanisms and new biological markers for GC patients with PM should be the direction of future studies. Furthermore, significant aspects of conversion therapy, such as timing and method of the operation, and the indications remain to be clarified.

Comparative proteomic analysis of human malignant ascitic fluids for the development of gastric cancer biomarkers

OBJECTIVES

Malignant ascites is a sign of peritoneal seeding, which is one of the most frequent forms of incurable distant metastasis. Because the development of malignant ascites is associated with an extremely poor prognosis, determining whether it resulted from peritoneal seeding has critical clinical implications in diagnosis, choice of treatment, and active surveillance. At present, the molecular characterizations of malignant ascites are especially limited in case of gastric cancer. We aimed to identify malignant ascites-specific proteins that may contribute to the development of alternative methods for diagnosis and therapeutic monitoring and also increase our understanding of the pathophysiology of peritoneal seeding.

DESIGN & METHODS

First, comprehensive proteomic strategies were employed to construct an in-depth proteome of ascitic fluids. Label-free quantitative proteomic analysis was subsequently performed to identify candidates that can differentiate between malignant ascitic fluilds of gastric cancer patients from benign ascitic fluids. Finally, two candidate proteins were verified by ELISA in 84 samples with gastric cancer or liver cirrhosis.

RESULTS

Comprehensive proteome profiling resulted in the identification of 5347 ascites proteins. Using label-free quantification, we identified 299 proteins that were differentially expressed in ascitic fluids between liver cirrhosis and stage IV gastric cancer patients. In addition, we identified 645 proteins that were significantly expressed in ascitic fluids between liver cirrhosis and gastric cancer patients with peritoneal seeding. Finally, Gastriscin and Periostin that can distinguish malignant ascites from benign ascites were verified by ELISA.

CONCLUSIONS

This study identified and verified protein markers that can distinguish malignant ascites with or without peritoneal seeding from benign ascites. Consequently, our results could be a significant resource for gastric cancer research and biomarker discovery in the diagnosis of malignant ascites.