Objective: Pancreatic cancer (PC) is a serious disease with poor outcomes, and its prevalence has been increasing steadily. The circadian rhythm (CR) is involved in multiple physiological events and maintains homeostasis. Alterations in the CR elevate the risk of developing cancer. The present case-control research was carried out to estimate the possible association between PERIOD2/PERIOD3 (PER2/PER3) gene variable number tandem repeat polymorphism (VNTR) variants and PC in the Turkish population. Materials and Methods: A total of 198 subjects (78 patients with PC and 120 healthy controls) were enrolled in this work. Genomic DNA was collected from peripheral blood mononuclear cells, and genotypic analyses was performed using a polymerase chain reaction (PCR) method. Odds ratio (OR) with a 95% confidence interval (95% CI) was calculated using the χ2 test. Results: The frequency of the 4R (4 repeats)/3R (3 repeats), 3R/3R genotypes, and 3R allele of PER2 VNTR in patients with PC was significantly higher than in the control group (p = 0003, p = 0.00004, respectively). PER2 VNTR 4/5 genotype was related to perineural invasion (p = 0.040). The genotype and allele distribution of PER3 VNTR variant did not show any statistical difference between the two groups (p > 0.05). The PER2/PER3 VNTR 4/5-4R/3R combined genotype was increased in the patient group (p = 0.013), while 4/5-4R/4R combined genotype was increased in the control group (p = 0.0001). Conclusions: Our work has indicated that PER2 VNTR 3R allele may play a crucial role in the pathogenesis of PC in Turkish patients, which may become a useful marker for predicting the development of PC. Furthermore, the PER2 VNTR genotype seems to be related to perineural invasion in PC.
Keywords: PCR; PER2; PER3; VNTR; cancer; pancreas.