Objective To identify the association between the insertion/deletion polymorphism of interleukin-1A gene (IL1A) and the susceptibility of prostate cancer (PCA). Methods We performed a case-control study enrolling 131 PCA patients and 229 healthy control subjects in a Chinese Han population. The TTCA insertion/deletion polymorphism (rs3783553) in 3′-UTR of IL1A gene was genotyped by PCR-RFLP method. Results The genotype distribution of rs3783553 in both groups met the requirements of Hardy-Weinberg equilibrium. Significantly reduced PCA risk was associated with D/I and I/I genotype compared to D/D genotype (P<0.001, OR=0.48, 95%CI: 0.31-0.74), and allele I is associated with the reduced PCA risk (P=0.001，OR=0.56，95%CI: 0.40-0.79). Conclusion TTCA insertion allele of rs3783553 contributes to the reduction of the susceptibility to prostate cancer.
