Purpose: Fas-Fas ligand (FasL)-mediated death pathway is important in the life and death of immune cells and, therefore, influences immune surveillance of carcinogenesis. This study examined the association between functional variants of Fas (-1377G-->A and -670A-->G), FasL (-844T-->C), and caspase-8 (CASP8) six-nucleotide deletion polymorphism (-652 6N ins-->del) and risk of pancreatic cancer.
Experimental design: Genotypes were determined in 397 cases with pancreatic cancer and 907 controls. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by logistic regression, and all statistical tests were two sided.
Results: We found a significant decrease in risk of pancreatic cancer associated with FasL and CASP8 but not Fas polymorphisms. Compared with noncarriers, the ORs of developing pancreatic cancer for FasL -844CT and TT carriers were 0.73 (95% CI, 0.57-0.94) and 0.35 (95% CI, 0.19-0.63), and for CASP8 -652 6N ins/del and del/del carriers were 0.65 (95% CI, 0.50-0.85) and 0.56 (95% CI, 0.33-0.98), respectively. Gene-gene interaction between the FasL and CASP8 variants further reduced the cancer risk in a multiplicative manner (OR for the presence of both FasL -844TT and CASP8 -652 6N del/del genotype, 0.10; 95% CI, 0.01-0.75). On the other hand, a multiplicative joint effect between the FasL -844CC or CASP8 -652 6N ins/ins genotype and smoking or diabetes mellitus in intensifying risk of pancreatic cancer was also evident.
Conclusions: These results suggest that genetic variations in the death pathway genes FasL and CASP8 are involved in susceptibility to developing pancreatic cancer.