Diminished quality of life in patients with cancer correlates with tryptophan degradation

Quality of life (QoL) is frequently impaired in patients suffering from malignant disease. Disturbed metabolism of neurotransmitter serotonin might be crucially involved, and serotonin-precursor tryptophan is degraded during pro-inflammatory immune response. In this study, we compared QoL and fatigue self-rating scores of patients with various types of malignancy with tryptophan metabolic changes and immune activation status.

Venous blood was collected from 146 patients with gastrointestinal tumors (n = 43), hematological malignancy (n = 40), gynecological neoplasms (n = 26), lung cancer (n = 20) and from tumors of other localization (n = 17).

QoL was significantly reduced in patients suffering from progressive tumor disease in comparison to stable or remitting disease, also feeling of fatigue was increased (both P < 0.001). Serum tryptophan concentrations were lower in patients with progressive disease (P < 0.01), and decreased tryptophan concentrations were related to decreased QoL (r _s = 0.256, P < 0.01) and increased fatigue (r _s = −0.179; P < 0.05). Concentrations of tryptophan and kynurenine and the kynurenine to tryptophan ratio were predictive for impaired QoL and increased fatigue in univariate regression analysis, in multivariate analysis higher ESR and neopterin concentration in combination with stage of disease predicted QoL deterioration.

Results suggest that immune-mediated tryptophan degradation may contribute to cancer-induced QoL deterioration.