The Distribution Of Gastric Elastic Fibers And Its Pathological Significance

Objective: To observe the distribution characteristics of Elastic Fibers(EFs)in the stomach wall and to explore the value of Peritoneal Elastic Lamina(PEL)in the pTNM stage and prognosis of gastric cancer.Methods: 60 normal gastric tissues and 75 cases of pT3 gastric adenocarcinoma were used to observe the distribution of EFs in the stomach wall during normal and gastric cancer.Focus on the distribution of PEL.For 75 cases of pT3 gastric cancer,one section containing the deepest tumor invasion partially or entirely covered with the peritoneum and the corresponding paraffin block were selected.All paraffin wax blocks were done routine HE staining and elastic staining.The staining results were observed and analyzed.30 cases of pT4 a gastric adenocarcinoma resected during the same period were examined for survival comparison.Results:(1)The normal gastric wall was rich in EFs and mainly consisted of four Elastic Lamina(EL),which were located in the muscularis mucosa,the junction between the muscularis propria and the submucosa,the junction between the muscularis propria and the subserosal tissue and the subserosal serosa respectively;the lamina propria of the mucosa,the submucosa,the connective tissue of the muscularis propria,the veins of the muscularis propria and the blood vessels also have EFs distribution.The subserosal EFs in the area where had no adipose tissue covered in the stomach wall filled almost the entire subserosal layer.The EL between the outer lamina propria and the PEL was unclear or merge into one EL in these area.The contents of EFs in different parts were different.From the cardia to the pylorus,the distribution of EFs in the muscular layer of the mucosa had a regular pattern with no significant changes.As to the EFs besides the muscularis propria,cardiac,gastric fundus,and body parts were more,but pylorus was less,PEL was thinner.The thickness and staining colour of EFs in different parts were different,at the four EL parts EFs were thicker,color were darker,but the EFs in the centre of muscularis propria were slender,and lightly stained.As to the EFs in the vessel,with the thickness of the wall,the thickness and the number of the EFs were increased.(2)There were no EFs in the tumors in gastric cancer and a small amount of EFs in the tumor stroma.PEL could be displaced or ruptured due to tumor-induced inflammation and fibrosis.The blood vessel wall was thickened,the inner elastic membrane was thicker,the color was deeper,and the outer membrane EFs content increased.There were two kinds of relationship between the tumor cells of gastric cancer and the PEL : no breakthrough and breakthrough.Among the 75 cases of pT3 gastric cancer,43 cases(57.3%)did not break through the PEL(pT3a),24 cases(32.0%)broke through the PEL(pT3b),and the PEL was unidentified in 8 cases(10.7%).(3)The clinicopathological data and survival analysis of 79 patients with follow-up data showed that the number of regional lymph node metastases in pT3 b gastric cancer was higher than that in pT3 a gastric cancer(p=0.02),and the lymphovascular invasion rate was higher than pT3 a gastric cancer(p=0.04),however,no significant difference was found in gender,age,tumor size,tumor location,pathological type,total lymph node count and N staging(p> 0.05).The former had a higher 3-year survival rate than the latter(76.7% vs 42.8%),and OS was higher than the latter(p<0.05).COX multivariate analysis found that PEL invasion and lymphovascular invasion were independent prognosis factors in the pT3 gastric cancer patients.There was no significant difference in the number of regional lymph node metastasis,lymphovascular invasion,gender,age,tumor size,tumor location,pathological type,total number of lymph nodes and N staging between pT3 b group and pT4 a group(p> 0.05).The former had a higher 3-year survival rate than the latter(42.8% vs 30.0%),and there was no statistical difference in OS(p>0.05).COX multivariate analysis found that age was an independent prognosis factor.There was no significant differences in the number of lymph node metastasis,lymphovascular invasion,gender,age,tumor size,tumor location,pathological type,total number of lymph nodes and N staging between pT3 and pT4 a groups(p> 0.05).The former had a 3-year survival rate higher than the latter(64.3% vs30.0%)and OS was higher than the latter(p<0.05).Univariate analysis revealed that serosal invasion,tumor size and lymphovascular invasion were poor prognostic factors in gastric cancer.COX multivariate analysis found that serosal invasion was an independent prognosis factor.Survival analysis of the three groups all showed that N stage was an independent prognosis factor.Conclusions:(1)The stomach is a muscular elastic fiber capsule.The stomach wall is rich in EFs and mainly has four EL.These EFs maintain the elasticity of the stomach and participate in their expansion.(2)PEL has a high recognition rate in gastric cancer,EFs staining can help determine the depth of tumor invasion,and then assess the location of the tumor and serosa,pT3 stage can be sub-categorized by PEL.(3)pT3 gastric cancer accompanied with PEL brokenthrough is a significantly adverse prognostic factor,it could be used to divide high-risk populations of gastric cancer.pT3 b gastric cancer could be treated as pT4 a gastric cancer.Therefore,when the depth of tumor infiltration exceeds the muscularis propria,in order to increase the standardization and accuracy of the pathological report and to give the clinician suggestion,elastic staining is necessary as a routine staining method,and the positional relationship between the tumor and the PEL is also necessary make a note.