Background: Anticancer drugs may frequently show host immunosuppression. Low-dose chemotherapy has been used for unresectable cancer as a tumor dormancy therapy, and it has been reported that the patients treated this way demonstrated favorable survival without toxicity. In this study, host immunity before and after a low-dose leucovorin plus 5-fluorouracil regimen (low-dose LV/5-FU) and S-1 plus irinotecan regimen (S-1/CPT-11) was compared to assess whether low-dose chemotherapy can maintain host immunity.
Patients and methods: Fourteen patients with recurrent or metastatic colorectal cancer underwent low-dose LV/5-FU, or S-1/CPT-11 treatment. The host immunity (cytokine production of the peripheral blood mono-nuclear cells (PBMC), serum soluble interleukin-2 receptor (sIL-2R) levels and phenotypic analyses of the PBMC) was measured before and after the first chemotherapy treatment.
Results: An increase of sIL-2R and CD4+CD25+ T cells with S-1/CPT-11 treatment, and a decrease with low-dose LV/5-FU treatment were observed and these changes in the first course were significantly different (p =0.0722 for the slL-2R, p=0. 0187for the CD4+CD25+ T cells).
Conclusion: The current study indicated that there is no change or an improvement in host immunity with the low-dose LV/5-FU treatment as compared with the S-1/CPT-11 treatment. Low-dose LV/5-FU treatment should be considered for metastatic colorectal cancer in order to maintain a host immunity during chemotherapy.