Omega-3 fatty acids for the treatment of cancer cachexia: Issues in designing clinical trials of dietary supplements

Complementary and alternative medicine (CAM) is increasingly popular, despite the limited evidence of the efficacy and safety of some forms of CAM. Cancer patients often turn to CAM therapies for the relief of treatment-induced side-effects and comorbidities. Cancer-associated weight loss commonly results in decreased functional status, life expectancy, and quality of life. Despite the high morbidity and mortality associated with cancer cachexia, mainstream treatments do not sustain weight. Although nutritional supplements are commonly used, many of these have not been tested in clinical trials. The issues faced in dietary supplement research differ from those in pharmaceutical drug trials. These include problems with standardization, contamination, and compliance documentation. A double-blind, randomized, placebo-controlled trial is proposed to evaluate the efficacy and safety of fish oil supplementation for the treatment of cachexia in pancreatic cancer patients. The primary outcome measure will be lean body mass; secondary outcomes include functional status and quality of life. The methodology of the clinical trial is reviewed here and the unique problems faced by investigators in designing studies of dietary supplements are discussed.