Detection of Bacterial DNA in Serum from Colon Cancer Patients: Association with Cytokine Levels and Cachexia

Background: There is increasing evidence that cancer cachexia patients have high cytokine levels, and bacterial translocation (BT) could increase cytokine secretion. Thus, we sought to investigate the relationship between BT and cancer cachexia.Methods: We studied colon cancer patients in our ward and healthy outpatient controls. Cancer patients were considered cachectic if they had lost > 10% of their pre-illness stable weight within 6 months and had serum CRP > 10 mg/L. Polymerase chain reaction (PCR) was used to detect bacterial DNA in serum from cancer patients and healthy controls. Cytokine levels were assessed using enzyme-linked immunosorbent assay (ELISA).Results: Bacterial DNA fragments were detected in 12 of 50 patients with cachexia (24.0%) and in 4 of 50 non-cachectic patients (8.0%). None of 89 healthy controls had bacterial DNA fragments in their serum. A statistically significant difference was found between cachectic and non-cachectic patients (p = 0.037, < 0.05) and healthy controls (p = 0.62×10-5, < 0.05). BT(+) cachectic patients had significantly higher levels of IL-1α, IL-6, IL-8, and TNF-α than healthy controls and BT(-) cachectic patients. CD3+ T, CD4+ T, CD4+ T/CD8+ T, and NK cell numbers were significantly lower in colon cancer patients than in healthy controls (p< 0.05), but CD8+ cell numbers were significantly higher in healthy controls than in cancer patients.Conclusions: Our results suggest for the first time that BT may contribute to cancer cachexia.