["Anticancer drugs may frequently induce host immunosuppression and symptomatic toxicities. Once symptomatic toxicity occurs, the patient's quality-of-life (QOL) is reduced. Since little is known of the relationship between host immunity and the toxicity of chemotherapy, the host immunity before and after chemotherapy was compared to assess whether it is related to symptomatic toxicity during chemotherapy.", 'Fourteen patients with colorectal cancer underwent leucovorin /5-fluorouracil (LV/5-FU) treatment, or S-1/irinotecan (CPT-11). Host immunity (cytokine production of peripheral blood mononuclear cell (PBMC), serum soluble interleukin-2 receptor (sIL-2R) levels and phenotypic analyses of PBMC were measured before and after the first chemotherapy.', 'An increase of sIL-2R, CD4+CD25+ T-cells and the CD4/8 ratio in patients with symptomatic adverse reactions were found. These changes in the first chemotherapy were significantly different (p = 0.0211, p = 0.0087, p = 0.0234).'] Do changes of immunological parameters reflect quality of life-related toxicity during chemotherapy in patients with advanced colorectal cancer?