Variability in the efficacies and toxicities of anticancer agents is a major problem. We hypothesized that polymorphisms in cytokine gene promoters may underlie genetic susceptibility to chemotherapy-induced toxicities in the Japanese. DNA was extracted from 100 patients undergoing 5-fluorouracil plus cisplatin chemotherapy. We used a case-only design to evaluate the relation between toxicities and cytokine promoter gene polymorphisms. The following polymorphisms were genotyped: tumor necrosis factor (TNF)-α-1031T/C, interleukin (IL)-1β-511C/T, IL-6-634C/G, IL-10-819T/C, IL-18-137G/C, macrophage migration inhibitory factor -173G/C, and 86-basepair variable numbers of tandem repeat in intron 2 of the IL-1 receptor antagonist. The frequency of the IL-6-634 GC and GG genotypes was significantly higher in patients with grades 1-4 leukopenia (P=0.003; Crude-odds ratios (Cr-OR) =4.0), neutropenia (P=0.0051; Cr-OR=3.6), or thrombocytopenia (P<0.0001; Cr-OR=6.1) than in patients without these toxicities. Similarly, the frequency of the IL-1β-511 TC and TT genotypes and the frequency of the TNF-α-1031 TT genotype were significantly higher in patients with grades 1-4 thrombocytopenia (P=0.015; Cr-OR=2.9) and stomatitis (P=0.02; Cr-OR=3.1), respectively. Multivariate analysis of factors such as age, sex, disease type, purpose of the chemotherapy, use of radiotherapy, and cytokine promoter gene polymorphisms showed polymorphisms to be significant predictors of toxicity. Our results suggest that polymorphisms in cytokine gene promoters may be associated with susceptibilities to leukopenia, neutropenia, thrombocytopenia and stomatitis in patients treated with 5-fluorouracil plus cisplatin.

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