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document
PSK may suppress CD57 ( + ) T cells to improve survival of advanced gastric cancer patients . BACKGROUND A recent report showed that oral adjuvant immunochemotherapy with protein-bound polysaccharide K ( PSK ) and tegafur/uracil ( UFT ) for stage II and III colorectal cancer improves overall survival compared with UFT alone . PSK has been supposed to improve survival through immunological mechanisms such as induction of cytokines , regulation of Th1/Th2 balance , and inhibition of immunosuppressive molecules . METHODS We investigated the mechanisms by which PSK influences immunological parameters such as Th1 cells ( IFN-gamma-positive CD4 ( + ) T cells ) , Th2 cells ( IL-4-positive CD4 ( + ) T cells ) , Th1/Th2 ratio , NKT cells ( CD56 ( + ) T cells and CD57 ( + ) T cells ) , NK cells , and CD25 ( + ) CD4 ( + ) T cells in stage III gastric cancer patients . Patients were randomly assigned to receive either 3 g PSK plus 300 mg UFT ( PSK group ) or 300 mg UFT alone ( control ) orally each day for at least 1 year following their operation . RESULTS Twenty-one registered patients with stage III gastric cancer were analyzed . The 3-year overall survival was 62.2 % in the PSK group ( n = 10 ) and 12.5 % in the control group ( n = 11 ) ( P = 0.038 ) . Before operation , there were no significant differences in the proportions of Th1 cells , Th2 cells , Th1/Th2 ratio , CD56 ( + ) T cells , CD57 ( + ) T cells , NK cells , and CD4 ( + ) CD25 ( + ) T cells between PSK and control groups . However , after operation , CD57 ( + ) T cells decreased significantly in the PSK group compared to the control ( P = 0.0486 ) . When all patients were analyzed , patients with increased proportion ( > 18 % ) of CD57 ( + ) T cells showed worse survival than those with lower ( < or = 18 % ) CD57 ( + ) T cells ( 3-year survival , 25.0 and 45.7 % , respectively ; P = 0.046 ) , consistent with our previous report that high CD57 ( + ) is an indicator of poor prognosis in patients with advanced gastric cancer . However , in the group treated with PSK + UFT , 3-year survival of CD57-high patients was as great as that of CD57-low patients ( 66.7 and 51.4 % , respectively ; P = 0.67 ) . CONCLUSION The present findings suggest that PSK improves overall survival of stage III gastric cancer patients partly by inhibiting CD57 ( + ) T cells , a proven poor prognostic factor in advanced gastric cancer .
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Intervention_Pharmacological
PSK
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Intervention_Pharmacological
oral adjuvant immunochemotherapy
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Intervention_Pharmacological
protein-bound polysaccharide K ( PSK )
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Intervention_Pharmacological
tegafur/uracil ( UFT )
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Intervention_Pharmacological
UFT
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Intervention_Pharmacological
PSK
44932
Intervention_Pharmacological
PSK
44933
Intervention_Pharmacological
PSK plus 300 mg UFT ( PSK group )
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Intervention_Pharmacological
UFT alone
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Intervention_Pharmacological
PSK
44936
Intervention_Control
control
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Intervention_Pharmacological
PSK
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Intervention_Pharmacological
PSK + UFT
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Intervention_Pharmacological
PSK
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Outcome_Physical
immunological parameters
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Outcome_Physical
Th1 cells ( IFN-gamma-positive CD4 ( + ) T cells ) , Th2 cells ( IL-4-positive CD4 ( + ) T cells ) , Th1/Th2 ratio , NKT cells ( CD56 ( + ) T cells and CD57 ( + ) T cells ) , NK cells , and CD25 ( + ) CD4 ( + ) T cells
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Outcome_Mortality
3-year overall survival
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Outcome_Physical
Th1 cells , Th2 cells , Th1/Th2 ratio , CD56 ( + ) T cells , CD57 ( + ) T cells , NK cells , and CD4 ( + ) CD25 ( + ) T
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Outcome_Physical
CD57 ( + ) T cells
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Outcome_Mortality
3-year survival