Differential cancer risk and survival in Indian oral cancer patients with genic region FAS and FASL polymorphisms.

OBJECTIVE: To investigate the association of genic region polymorphisms of FAS and FASL in Indian patients with oral cancer. STUDY DESIGN: The study included 960 consenting control participants and patients with oral cancer. Genotyping was performed using Polymerase Chain Reaction -Restriction Fragment Length Polymorphism (PCR-RFLP). Cancer risk, 5-year survival, and hazards ratio (HRs), with respect to risk and clinical factors, were estimated using Fisher's exact test, Kaplan-Meier analysis, and Cox proportional hazards models. RESULTS: FASL IVS2nt-124 'AG' increased risk in males with buccal mucosa cancer (BMC) but decreased risk in females. FAS 21196 'CT' decreased risk of tongue cancer (TC) and BMC in females. The survival of the patients also differed between sexes in TC and BMC. FAS 21196 'CT' increased HR by 23-fold in females with BMC when adjusted for age, stage, grade, LVS, PNI, tobacco use, and alcohol. 'TT' genotype increased the HR in females with BMC when adjusted for age, stage, grade, lymphovascular spread (LVS), perineural invasion (PNI), and perinodal spread (PNS). Our bioinformatic study revealed the presence of CTCF binding regions and CpG islands near FAS and FASL. CONCLUSIONS: These single nucleotide polymorphisms (SNPs) altered the risk and survival of BMC and TC patients differentially that varied with clinical and risk factors.