Elevated Serum AA/EPA Ratio as a Predictor of Skeletal Muscle Depletion in Cachexic Patients with Advanced Gastro-intestinal Cancers

Background: In recent years, the number of cancer patients has increased. Cancer patients are prone to sarcopenia as a result of the decrease in muscle mass and muscle weakness which occurs in cancer cachexia. Attention has been given on the effects of fatty acid administration on cancer patients. Materials and Methods: We conducted a retrospective chart-review study of consecutive patients with unresectable advanced GI cancer (stage IV) (n=46) receiving chemotherapy treatment in an outpatient or inhospital setting between December 2012 and September 2015 at our Institution. The collected data were characteristics, psoas muscle area as measured by computed tomography (CT), and biochemical blood test and serum fatty acid profiles. Three methods of analysis were evaluated: (i) Comparison of biomarkers between two groups: psoas muscle index change rate (Delta PMI) decrease group vs. Delta PMI increase group. (ii) Correlation between Delta PMI and biomarkers. (iii) Multiple regression of Delta PMI and biomarkers Results: In the Delta PMI decrease group, n-6/n-3 ratio and AA/EPA ratio in the decrease group were significantly higher than those in the increase group. Among all parameters, serum EPA was positively and significantly related to Delta PMI (CC=0.443, p=0.039). In contrast, serum CRP, AA/EPA ratio and n-6/n-3 ratio were negatively related to Delta PMI (CC=-0.566, CC=-0.501, CC=-0.476, p=0.006, p=0.018, p=0.025, respectively). On multiple regression analysis, serum CRP value was strongly related to Delta PMI (r(2)=0.421, beta=-0.670, p=0.001). Conclusion: Higher n-6/n3 and AA/EPA ratios were associated with a decrease in psoas muscle area, that lead to diagnosis of sarcopenia. Higher CRP was also associated with a decrease in psoas muscle area, suggesting that this might be an indicator of cachexic skeletal muscle depletion in cachexic patients with advanced gastro-intestinal cancers.