Relationship of Amplification and Expression of the C-MYC Gene with Survival among Gastric Cancer Patients

Background: During the past decades, the incidence and mortality rate of stomach cancer has demonstrateda great decrease in the world, but it is still one of the most common and fatal cancers especially among menworldwide, including Iran. The MYC proto-oncogene, which is located at 8q24.1, regulates 15% of genes and isactivated in 20% of all human tumors. MYC amplification and overexpression of its protein product has beenreported in 15-30% of gastric neoplasias. The aim of this investigation was to find the relative efficacy of CISH(chromogenic in situ hybridization) or IHC (immunohistochemistry) in diagnosis and prognosis of gastric cancer,as well as the relationship of amplification and expression of C-MYC gene with patient survival. Materials and
Methods: In this cross-sectional study, 102 samples of gastric cancer were collected from patients who hadundergone primary surgical resection at the Cancer Institute Hospital, Tehran University of Medical Sciences,from July 2009 to March 2014. All samples were randomly selected from those who were diagnosed with gastricadenocarcinomas. CISH and IHC methods were performed on all of them.
Results: Patients were classifiedinto two groups. The first consisted of stage I and II cases, and the second of stage III and IV. Survival tests forboth groups was carried out with referrnce to CISH test reults. Group II (stage III & IV) with CISH+ featuredlower survival than those with CISH- (p=0.233), but group I (stage I & II) patients demonstrated no significantvariation with CISH+ or CISH- (p=0.630). Kaplan-Meier for both groups was carried out with IHC test findingsand showed similar results. This data revealed that both diffuse and intestinal types of gastric cancer occurredsignificantly more in men than women. Our data also showed that CISH+ patients (43%) were more frequentin comparison with IHC+ patients (14.7%).
Conclusions: For planning treatment of gastric cancer patients, byfocusing on expanding tumors, which is the greatest concern of the surgeons and patients, CISH is a better andmore feasible test than IHC, in regard to sensitivity and specificity. Therefore, CISH can be used as a feasible testfor tumor growth and prognosis in stage III and IV lesions. This study also indicated that C-MYC amplificationin gastric cancer is correlated with survival in advanced stages.