Association between polyunsaturated fatty acids in adipose tissue and mortality of colorectal cancer patients

Introduction: Nutritional intake and dysregulation of fatty acid metabolism play a role in the progression of various tumors, but the consumption of fatty acids is difficult to assess accurately with dietary questionnaires. Biomarkers can objectively assess intake, storage and bioavailability.

Objective: We studied the association between the polyunsaturated fatty acid (PUFA) composition of abdominal subcutaneous adipose tissue (good indicator of dietary intake over 2-3 years) and all-cause mortality.

Methods: In the multicenter AGARIC study, samples from 203 patients with colorectal cancer (CRC) undergoing curative surgery, were harvested from subcutaneous adipose tissue, which were then analyzed for PUFA composition.

Results: After a median follow-up of 45 months, 76 patients died. These patients were more often men (72.4% versus 57.5%, P = 0.04), diabetic (32.9% versus 13.4%, P = 0.001), old (median: 74.5 versus 66.6 years, P < 0.001) and with high alcohol consumption (47.4% versus 30.7%, P = 0.005). An increased risk of death was observed with higher levels of 20:2 ω-6 (hazard ratio_{tertile3 vstertile1} (HR_T3vsT1) 2.12; 95% confidence interval (CI) 1.01-4.42; p-trend = 0.04), 22:4 ω-6 (HR_T3vsT1 = 3.52; 95% CI = 1.51-8.17; p-trend = 0.005), and 22:5 ω-6 (HR_T3vsT1 = 3.50; 95% CI = 1.56-7.87; p-trend = 0.002). Conversely, the risk of death seemed lower when higher concentrations of 18:3 ω-6 (HR_T3vsT1 = 0.52; 95% CI = 0.27-0.99; p-trend = 0.04) and the essential fatty acid, α-linolenic acid 18:3 ω-3 (HR_T3vsT1 = 0.47; 95% CI = 0.24-0.93; p-trend = 0.03) were observed.

Conclusion: The risk of death was increased in CRC patients with higher concentrations of certain ω-6 PUFAs and lower concentrations of α-linolenic acid in their subcutaneous adipose tissue. These results reflect dietary habits and altered fatty acid metabolism. Our exploratory results warrant confirmation in larger studies with further exploration of the mechanisms involved.