Associations between single-nucleotide polymorphisms of the interleukin-18 gene and breast cancer in Iraqi women

According to long-term projections, by 2030, the world’s population is predicted to reach 7.5 billion individuals, and there will be roughly 27 million new cancer cases diagnosed. The global burden of breast cancer (BC) is expected to rise. According to the Ministry of Health-Iraqi Cancer Registry, cancer is the second largest cause of death after cardiovascular disease. This study investigated the interleukin-18 (IL18) single-nucleotide polymorphisms (SNPs) –607C/A rs1946518 and –137G/C rs187238 using the sequence-specific amplification-polymerase chain reaction approach. Regarding the position –607C/A, there was a highly significant difference between the observed and expected frequencies in patients and controls (χ(2) = 3.16 and χ(2) = 16.5), respectively. The AA and CA genotypes were associated with significantly increased BC risk (odds ratio [OR], 3.68; p = 0.004 and OR, 2.83; p = 0.04, respectively). Women with the A allele had a 5.03-fold increased susceptibility to BC. The C allele may be a protective allele against BC (OR, 0.19). Although position –137G/C showed no significant differences in the CC genotype distribution (p = 0.18), the frequency of the CC genotype was significantly higher in patients than in controls. In contrast, patients had a significantly higher frequency of GC genotypes than controls (p = 0.04), which was associated with an increased risk of developing BC (OR, 2.63). The G allele frequency was significantly lower in patients than in controls (55.0% vs. 76.2%, respectively). This SNP may be considered a common genotype in the Iraqi population, with the wild-type G allele having a protective function (OR, 0.19) and the mutant C allele having an environmental effect (OR, 2.63).