Study On The Relationship Between IGF-1 Gene Polymorphism And The Risk Of Stomach Cancer

Objective: To explore the relationship between insulin-like growth factor-1 (IGF-1) gene polymorphism and the risk of stomach cancer.Methods: A hospital-based 1:1 case-control study was conducted among 100 stomach cancer patients and 100 controls. The questionnaire included items on smoking status, alcohol consumption, diet and drinking habit, et al. Each of cases and controls provided 5ml peripheral bloodsample to extract DNA. PCR-RLFP technique was used for analyzing genotypes of IGF-1. The risk factors were screened by simple conditional logistic regression model. The interaction between genes and environmental risk factors was analyzed by multivariate logistic regression model. In addition, the present study wants to show if IGF-1 C genotype might interact with frequent consumption of pickled food and drinking to increase the risk of stomach cancer.Result: The study showed the risk factors related with stomach cancer were frequent consumption of pickled food, often eating hard food, deep of drinking, strongly mental incentive and family history of digestive tumor; a protective factor related with stomach cancer were good education. PCR-RLFP technique was used for analyzing genotypes of IGF-1. Among case with stomach cancer, the frequency of A/A, A/C, C/C genotype were 42%,44%,14%, compared withcontrols as 51%,42%,7% respectively. Using A/A genotype as reference, the OR of A/C or C/C genotype was 1.44(95%CI:1.09～1.91). 64% A and 36% C allele were distributed in stomach cancer case, while 72% A and 28% C in controls. The OR for C allele in relation to A allele was 1.45(95%CI: 1.17 ～ 1.80) when A allele was used as reference. The results showed that the polymorphisms of IGF-1 were related to the susceptibility of stomach cancer. The A/C or C/C genotype frequency was significantly higher in the cases than controls. C allele might interact with frequent consumption of pickled food to increase the risk of stomach cancer. The attributable proportion of interaction for C allele interaction with frequent consumption of pickled food was 0.43(API=0.43), the synergy index was 2.91(S=2.91), the relative excess risk of interaction was 1.22(RERI=1.22). No interaction was observed between IGF-1 A genotype and alcohol drinking.Conclusion: IGF-1 A/C or C/C genotype might increase the risk of stomach cancer development and the genotype might also interact with frequent consumption of pickled food to increase the risk of stomach cancer.