We investigated risk association of oral cancers (tongue and buccal mucosa cancers) with FAS (-1377G > A and FAS -670 A > G) and FASL (-844 T > C) SNPs, in males and females. A case-control study of 535 oral cancer and 525 control subjects was performed. SNPs were detected in the genomic DNA isolated from peripheral blood using PCR-RFLP. We report FASL -844 T > C SNPs increased risk for buccal mucosa cancer in females but not in males. On the other hand, FAS genotypes did not alter the risk of the cancers in both females and males. However, co-occurrence of FAS -1377 GA and -670 GG, FAS -1377 AA and -670 GG genotypes, and combined genotypes of FAS and FASL (FAS -1377 AA + FAS -670 GG + FASL -844 CC) alter male susceptibility towards tongue cancer. In females, combined genotypes of FAS (-1377GA and -670 AA) were found to be a risk factor of buccal mucosa cancer (OR = 3.27, CI = 1.28-8.36; P ≤ 0.01). FASL variants (GA and AA) increased tongue cancer risk in females who were tobacco users compared to non-tobacco users. In conclusion, SNPs of the FAS and FASL might alter risk of tongue and buccal mucosa cancers differentially, in a gender-dependent manner.

We investigated risk association of FAS (-1377 G>A and -670 A>G) and FASL (-844 T>C) promoter polymorphisms with breast, ovarian, cervical, and endometrial cancers and report that the FASL -844 CC genotype was protective against breast, ovarian, cervical, and endometrial cancers (P ≤ 0.01). On the other hand, FAS -1377 GA and AA variants increased risk of breast cancer. However, the GA variant of FAS -1377 was also found to be a risk factor for cervical cancer. In contrast, FAS -670 AG variant significantly lowered risk of breast cancer. Further, we also observed that risk association of co-occurrence of FAS and/or FASL variants with the cancers varied as compared to the presence of individual polymorphisms. Although risk and protective haplotypes of FAS SNPs were observed across the cancer phenotypes, the association of the haplotypes was significant for breast cancer alone with a 3-fold enhanced risk. The protective effect of the FASL CC genotype seen in this study suggests that similar biomolecular mechanisms involving FASL might play a role in female-specific cancers.

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