Serum tryptophan decrease correlates with immune activation and impaired quality of life in colorectal cancer

Area of Science:

• Immunology
• Oncology
• Biochemistry

Background:

• Cancer-related indoleamine (2,3)-dioxygenase (IDO) up-regulation by interferon-gamma (IFN-γ) may impact quality of life (QoL) by depleting serum tryptophan.
• IDO is an enzyme involved in tryptophan metabolism, and its activity is associated with immune responses and cancer progression.

Purpose of the Study:

• To investigate the correlation between serum tryptophan levels, immune activation markers, and quality of life in patients with colorectal liver metastases.
• To determine if serum tryptophan is an independent predictor of QoL in this patient population.

Main Methods:

• Serum levels of tryptophan, kynurenine, neopterin, IL-2 sRα, sTNF RI, IL-6, and CRP were measured in patients with colorectal cancer and colorectal liver metastases.
• Quality of life and psychological questionnaires (Rotterdam Symptom Checklist, Sickness Impact Profile) were administered.
• Liver metastasis volume was assessed by CT, and survival data were collected.

Main Results:

• Reduced serum tryptophan was significantly associated with poorer physical symptom scores on the Rotterdam Symptom Checklist and the Sickness Impact Profile.
• Lower tryptophan levels correlated with increased markers of immune activation, including neopterin, IL-2 sRα, and sTNF RI.
• Serum tryptophan emerged as an independent predictor of physical symptom burden and overall impact on quality of life.

Conclusions:

• The findings support a role for IFN-γ-mediated tryptophan depletion in cancer-induced deterioration of quality of life.
• Targeting IDO or managing tryptophan levels could be potential strategies to improve QoL in cancer patients.