Fish Oil Decreases the Severity of Treatment-related Adverse Events in Gastrointestinal Cancer Patients Undergoing Chemotherapy: A Randomized, Placebo-controlled, Triple-blind Clinical Trial

Background And Aims: Due to its high peroxidizable characteristics, n-3 fatty acids, present in fish oil, could increase tumor cells sensitivity to conventional cancer treatment while non-neoplastic cells remain unaffected, this may lead to an increase in cancer treatment response with no increase on adverse effects. The aim of this study was to evaluate anti-cancer treatment response, performance status and adverse events in gastrointestinal cancer patients supplemented with fish oil. Oxidative stress parameters were investigated in blood non-neoplastic cells as an indicator of cytotoxicity.

Methods: This is a randomized, triple-blind, placebo-controlled clinical trial. Fish oil group (FOG) received two capsules of fish oil containing 1.55 g of EPA + DHA a day for nine weeks, placebo group (PG) received two capsules containing olive oil. Baseline was set right before the administration of the first chemotherapy, oxidative stress parameters, adverse events presence and grading and performance status were assessed at baseline and after nine weeks of supplementation. Tumor markers, response to treatment and survival were evaluated at baseline and after one year of study inclusion.

Results: 76 patients were considered eligible, 56 were randomized, and 51 remained for analysis. After nine weeks, although there were no differences between groups for treatment response and presence of adverse events, PG patients were graded with more severe diarrhea than FOG patients (p = 0.03) and with higher (worse) performance status score (p = 0.02). No differences in lipid peroxidation and activity of antioxidant enzymes were observed between groups.

Conclusions: Fish oil may lead to a better performance status for gastrointestinal cancer patients undergoing chemotherapy while does not seem to increase treatment-related toxicity. Registered under ClinicalTrials.gov Identifier no. NCT02699047, www.clinicaltrials.gov.