Multicenter trial for assessing cytokine promoter gene polymorphism as a predictive parameter of PSK responder for curatively resected stage II or III colorectal cancer.
619 Background: Polysaccharide-K (PSK), a protein-bound polysaccharide extracted from the mycelia of Coriolus versicolor, is an immunomodulator widely used in colorectal cancer in Japan. PSK has immunological actions including enhancement or inhibition of cytokine production. It has been reported that levels of cytokine production are influenced by polymorphisms in the promoters of cytokine genes. We hypothesized that cytokine promoter gene polymorphisms may be responsible for genetic susceptibilities to immunological effect of PSK. Methods: This is a multicenter prospective trial. One hundred and ten patients with stage II or III colorectal cancer were enrolled. All patients received adjuvant immnochemotherapy after curative resection using UFT (stage II) or UFT/LV (stage III) combined with PSK (3.0 g/day, p.o.) for 1 year. Post-operative survey of recurrence was followed with CT scan at 6-month intervals during the first 2 years after surgery and at 1-year intervals thereafter until 5 year after surgery. DNA was extracted from peripheral blood cells in all patients. The following polymorphisms of the patients were genotyped: TNF-α-1031T/C, IL-1ß-511C/T, IL-6-634C/G, IL-10-819T/C. Results: Twenty (6 in stage II, 14 in stage III) out of 110 patients showed recurrence after more than 5 years survey. Fifteen out of 74 patients with TNF-α-1031 TT genotype and 5 out of 36 with TNF-α-1031 CC or CT showed disease recurrence. Five out of 39 patients with IL-1ß-511 CC and 15 out of 71 with IL-1ß-511 CT or TT showed disease recurrence. Eleven out of 61 patients with IL-6-634 CC and 9 out of 49 with IL-6-634 CG or GG showed disease recurrence. No association between genotype frequency and disease recurrence was observed for TNF-α, IL-1ß, IL-6. Fifteen out of 61 patients with IL-10-819 CC or CT genotype showed disease recurrence, whereas only 5 out of 49 with IL-10-819 TT showed tumor recurrence (p=0.052). Especially, significant association with disease recurrence was found in stage III patients (12/30 vs 2/17, p=0.042). Conclusions: It is suggested that colorectal cancer patients with IL-10-819 TT genotype could be PSK responder after curative resection.