| 1Backgroud and PurposeEsophageal cancer (EC) is one of the six most common vicious tumors in the world, regional distribution of significant differences is the prominent feature of EC. On the other hand, gastric cardia adenocarcinoma (GCA) is similar to EC in geographical distribution. China is the country with the highest incidence and mortality rate for EC/GCA in the world, especially in Taihang Mountain area at the junction of Henan, Hebei and Shanxi provinces, the highest incidence area in China, and also in the world. It has been illustrated that environmental factors play an essential role in the development of EC/GCA. Furthermore, in these high incidence areas, EC/GCA shows conspicuous familial aggregation, which point out that genetics factors may also play an important role in the development of EC/GCA.Twins is of two types, including monozygotic twin (MZ) and dizygotic twin (DZ). MZ refers the two fetals developed from one fertilized egg, and the two members have exactly the same genetic materials and chromosomes; DZ refers the two fetals developed from different fertilized eggs, and the genetic materials and chromosomes of the two members are partly (50%) the same. Because of the special genetic background of the twins, it helps to exclude the bias brought by genetic and environmental, and has a positive meaning to clarify the interaction of environmental and genetic factors in upper gastrointestinal tumors.In this study, epidemiological investigations, egg-type identification, endoscope and histopathological examination were proformed on asymptomatic twins in the EC/GCA high incidence areas in Henan province, and compare the results of endoscope and histopathological changes at gastric body and antrum in MZ and DZ, to further illustrate the genetic and environmental factors on the development of gastric precancerous and cancerous lesions.2Materials and Methods2.1SubjectsIn this study, all the subjects were collected from the EC/GCA high incidence areas (Linzhou, Anyang, Hebi, et al) in Henan province, and exclude a single inspection of twins, total of190pairs of information integrity twins were selected, and the two members both were received endoscope examination. Among the190pairs of twins, there were104males, age range is33-71, and the average age was50±2;86females, age range was34-76, and the average age was52±2. And the twins can be divided into147pairs MZ and43pairs DZ.2.2Survey methodsAfter a large-scale field surveys, household interview surveys and telephone follow-up in high incidence areas, the research group signed informed consent forms with the twins who accepted the survey, and then complete the registration form. The main survey include:general information, medical history, personal habits, general physical examination, laboratory tests, twin family history, etc. The cancer patients, especially the EC/GCA patients, asked detailly about the family history of cancer and draw a family pedigree chart. Carried out fingerprint check on the two members of the twins, and extracted fasting peripheral venous blood5ml (EDTA-K2anticoagulant) of each twin members, then divided into2tubes, and stored in the super cold (-40℃/-80℃) refrigerator. Finally, carried out endoscope examination and take biopsies of each twin members.2.3Endoscope examinationEndoscopic and biopsy examinations were performed on190pairs of twins. Two pieces of biopsy were taken from the middle and lower segment of the esophagus, cardia, gastric body and antrum, and additional biopsy would be taken randomly at visible lesions. One piece of biopsy tissues was immediately fixed with85%alcohol, and another one was stored in-80℃refrigerator.2.4Egg-type identificationTwo methods were taken to identify the egg-types of190pairs of twins. Among them,116pairs were used a combination of ABO blood typing, similar diagnosis and questionnaire, the other74pairs were extracted whole blood DNA and used short tandem repeat (STR) sequencing, which also called microsatellite DNA genotyping technology, this is an accurate and reliable identification method, and used as the gold standard of identification of twin egg-types.2.5Histopathological diagnosisAccording to the changes in epithelia cell morphology and tissue structure, the gastric epithelia were divided into normal (NOR), chronic superficial gastritis (CSG), chronic atrophic gastritis (CAG), intestinal metaplasia (IM) and anaplastic/dysplasia (DYS), etc. Histopathological diagnosis was performed by two pathologists independently.2.6Statistical methodAll the data were analyzed using the SPSS19.0software. Chi-square test was applied for egg-type identification, histopathological changes. The inspection significant level was considered as P<0.05.3Results3.1Egg-type identification resultsMake use of the questionnaire,116pairs of twins can be divided into95pairs of MZ and21pairs of DZ, and another74pairs of twins that used genetic diagnosis method can be divided into52pairs of MZ and22pairs of DZ. The calculation results demonstrate that the two identification methods showed no statistically significant (χ2=3.488, P=0.062, P>0.05).3.2Pathological results of gastric body and antrum biopsyThere were71pairs of twins all had the gastric body biopsy,119pairs were excluded because of only one member was taken biopsy or the biopsy was too small to be diagnosed, and the histopathological diagnosis showed:63cases of NOR were detected, the two members both were had normal gastric body were19pairs, and can be divided into15pairs of MZ and4pairs of DZ, the twins that one member was normal but the other one had other lesions were25pairs;72cases of CSG were detected,20pairs of double, included15pairs of MZ and5pairs of DZ, and32singles;4cases of CAG were detected, all were singles, contained3pairs of MZ and1pairs of DZ;2pairs of IM and DYS were detected, all were singles, MZ.There were142pairs of twins all had the gastric antrum biopsy,48pairs were excluded because of only one member was taken biopsy or the biopsy was too small to be diagnosed, and the histopathological diagnosis showed:53cases of NOR were detected, the two members both were have normal gastric antrum were10pairs, and can be divided into8pairs of MZ and2pairs of DZ, the twins that one member was normal but the other one had other lesions were33pairs;178cases of CSG were detected,66pairs of double, included49pairs of MZ and17pairs of DZ, and46singles;39cases of CAG were detected,10pairs of double, includes5pairs of MZ and5pairs of DZ, and19singles;28cases of DYS were detected,3pairs of double, all were MZ, and22singles.3.3Total consistent rate of Pathological results of gastric body and antrum biopsyThe consistent rate of pathological results on gastric body in male was65.7%(23/35), in female was44.4%(16/36), and the total consistent rate was54.9%(39/71); on gastric antrum in male was62.0%(44/71), in female was59.2%(42/71), and the total consistent rate was60.6%(86/142); the pathological results of the gastric body and antrum consistency in different genders had no statistical significant(χ2gastric body=3.243, P=0.072, P>0.05;χ2gastric antrum=0.118, P=0.731, P>0.05). And the total consistency of the pathological results between gastric body and antrum had no statistical significant (χ2gastric body vs. gastric antrum=0.620, F=0.431, P>0.05).The consistent rate of pathological results on gastric body in MZ was53.6%(30/56), in DZ was60.0%(9/15), and the total consistent rate was54.9%(39/71); on gastric antrum in MZ was60.7%(65/107), in DZ was62.9%(22/35), and the total consistent rate was61.3%(87/142); the pathological results of the gastric body and antrum consistency in different egg-types had no statistical significant(χgastric body=0.197, P=0.675, P>0.05;χ2gastric antmm=0.049, P=0.824, P>0.05). And the total consistency of the pathological results between gastric body and antrum had no statistical significant (χ2gastric body vs. gastric antrum=0.787, P=0.375, P>0.05).3.3The consistent rate of gastroscopy and pagthological examinationAmong the190pairs of twins who received gastroscopy, exclude no biopsy or the biopsy was too small to be diagnosed, within the gastroscopy results NOR twins,22cases of NOR,42cases of CSG and12cases of CAG were detected by histopathological examination; within the gastroscopy results CSG twins,32cases of NOR,124cases of CSG and26cases of CAG were detected; within the gastroscopy results CAG twins,4cases of CSG and2cases of CAG were detected. Gastroscopy and pathological examination in all levels of lesions, the diagnosis results in the two diagnostic methods in the consistent rate less than the inconsistent rate (χ2=0.110, P=0.019).4ConclusionsThere is a lower consistency between the two members of the twins in gastric body and antrum in various diseases, suggesting that the environmental factors may play an predominant role in the development of gastric cancer. |
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