Characteristics Of Gene Mutation And Their Associations With Clinicopathological Features In 270 Cases With Gastrointestinal Stromal Tumor

Objective:To study the relationship between C-kit and PDGFRA gene mutations and their characteristics and clinicopathological features in 270 patients with gastrointestinal stromal tumors.Methods:A total of 270 patients with gastrointestinal stromal tumor admitted to the First Affiliated Hospital of Chongqing Medical University from June2016 to January 2019 were retrospectively analyzed.Results:1.There are 133 males and 137 females among 270 patients.The median age of onset was 58 years.144 cases(53.3%)were in the stomach,94 cases(34.8%)in the small intestine,9 cases(3.3%)in the rectum,4cases(1.5%)in the colon,and 19 cases(7.0%)in other sites(oesophagus,pelvic cavity or retroperitoneum).The largest tumor size was ≥5,< 10cm(46.3%),the mitotic figure was < 5 / 50HPF(54.8%)and NIH wasclassified as high risk(53.7%)are the most of the patients.The majority of the patients(96.3%)were operated.2.C-kit mutations were detected in 220(81.5%)of 270 patients,including 190(70.4%)mutations in exon c-kit11,26(9.8%)mutations in exon 9,9(3.3%)mutations in exon 13 and 6(2.2%)mutations in exon 17.Exon 9 mutation was A502-Y503 repeat mutation,and the main site of disease was small intestine(69.2%).Exon 11 had a wide variety of mutations,mainly deletion and point mutations.Most of the mutations occurred at 550-580 sites,with 557-560 being the most prominent.Exon 13 and exon 17 were point mutations.PDGFRA mutation was detected in 7cases(2.6%),including exon 12 mutation in 3 cases(1.1%)and exon 18 mutation in 4 cases(1.5%).Exon 18 was mostly D842 V mutation(75%).Dog-1 was positive in 263 cases(97.4%),CD117 positive in 263 cases(97.4%),CD34 positive in 235 cases(87.0%),S100 positive in 28 cases(10.4%),SMA positive in 68 cases(25.2%).3.The proportion of maximum tumor diameter less than 5cm in female patients was higher than that in male patients(p=0.013).The proportion of mitotic figures < 5 / 50 HPF in wild type patients was significantly higher than that in patients with c-kit and PDGFRA mutations(p=0.027).The positive rate of CD117 in wild type was lower than that in mutant type(p<0.05).The positive rate of SMA in wild type was higher than that in Mutant type(p=0.002),and the frequency of PDGFRA mutation inpatients over 50 years old was higher than that in other types(p=0.040).C-kit9 mutation occurred more frequently in the small intestine than other mutations(p < 0.05).The probability of c-kit11 midpoint mutation and mixed mutation in stomach was lower than other types of mutation(p=0.022).Conclusion:Stomach is the most common location of GIST.C-KIT and PDGFRA mutation rate is high and the mutation type is various.C-kit 11 exon mutation is the most common mutation type of GIST.The majority of GIST cases were CD117 and DOG-1 positive.The type of c-kit11 mutation is related to the site of the disease.The prognosis of PDGFRA mutation patients is worse than that of c-kit mutation patients.The primary site of c-kit9 mutation patients is on small intestine.The prognosis of wild type patients is better than that of mutation patients.The mutation type and locus are various,the different patient should adopt the different treatment method.