Glutathione S-transferase M1, T1 null genotype, smoking, diet and susceptibility of colorectal cancer
aDepartment of Epidemiology and Health Statistics, Zhejiang University school of Public Health, Hangzhou 310031, China, bInstitute of cancer prevention and control in Jiaoshan, Jiashan 314000, China, cInstitute of cancer research, Zhejiang University, Hangzhou 310031, China
Aim: To investigate the relationship between Glutathione S-transferase M1 and T1 polymorphisms as well as the interaction of smoking status and fried-food intake and colorectal cancer susceptibility. Methods: A case-control study of 126 patients and 343 health controls was conducted to investigate the role of GSTM1 and GSTT1 polymorphisms in colorectal cancer. Genotypes of GSTM1 and GSTT1 polymorphisms were analyzed by multiplex allele-specific polymerase chain reaction (PCR). The dietary fried-food intake assessed using food-frequency questionnaire. The unconditional logistic regression was applied to estimate the OR and its 95%CI. Results: The frequency of GSTM1 null and GSTT1 null genotypes was 55.46% and 20.35%, respectively. After adjustment for age and sex, the GSTM1 null genotype had a significantly increased risk of rectal cancer compared to GSTM1 non-null genotype (OR=9.74, 95%CI, 1.13-83.85) among those with GSTT1 null genotype. A 2.22-fold increased risk of rectal cancer was associated with GSTM1 null genotype compared to GSTM1 non-null genotype among current smokers. In men with GSTT1 null genotype and current smoking had a significant risk of colon cancer (OR=4.55, 95%CI, 1.14-18.17), and rectal cancer (OR=4.60, 95%CI, 1.11- 19.11). A strong obverse association was observed between the risk of colon cancer and GSTT1 null genotype carriers with the highest fried-food intake (OR=5.60, 95%CI, 1.75-17.91). Conclusion: This study suggests that certain null GSTM1 and GSTT1 genotypes may associate with an elevated risk of colorectal cancer and the association may be modified by interaction of two genetic polymorphisms and cigarette smoking, fried-food intake.
Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in poster session 996 (Genetic & environmental interactions).