Interleukin-1β Gene (IL-1B) rs16944 (-511 C > T) Promoter Polymorphism Is Associated with Cutaneous Melanoma Susceptibility, Stage, and Anatomical Localization in a Northern Italian Case–Control Study

Immunity plays critical roles in cutaneous melanoma. We investigated the association between the pro-inflammatory interleukin-1β gene (IL-1B) rs16944 (-511 C > T) promoter single nucleotide polymorphism (SNP) and cutaneous melanoma susceptibility and clinical features. This observational case–control study included 133 patients with cutaneous melanoma and 900 healthy controls from Northeastern Italy. The rs16944 C > T polymorphism was determined by genomic DNA restriction fragment analysis. The IL-1B rs16944 C allele (OR = 1.44, p = 0.014) and CC genotype (OR = 1.48, p = 0.037) were associated with modestly higher odds of melanoma. Among melanoma patients, the CC genotype was associated with Stage I disease (OR = 2.45, p = 0.016) and Breslow thickness ≤ 0.75 mm (OR = 2.27, p = 0.049), whereas it was less frequent in Stage IV melanoma (OR = 0.37, p = 0.029). The CT genotype was associated with Stage IV melanoma (OR = 3.03, p = 0.014) and with lower-limb (OR = 2.45, p = 0.038) and lower-extremity (OR = 3.09, p = 0.005) melanoma. These divergent associations are exploratory and do not establish disease trajectory or a functional effect of rs16944; mechanistic interpretation remains uncertain because IL-1β expression or activity was not measured in this cohort. To our knowledge, this is the first report of an association between a genetic polymorphism and lower-limb/lower-extremity melanoma. These exploratory findings require confirmation in independent cohorts.