Fish Oil Supplements May Improve Cancer Therapies’ Effectiveness

DALLAS—A preclinical study suggests that adding fish oil to the diet of a cancer patient might increase the effectiveness of cancer therapies and improve the patient’s outcome, W. Elaine Hardman, PhD, of the University of Texas Health Science Center at San Antonio, said at the Susan G. Komen Foundation’s 1999 National Grant Conference.

Dr. Hardman and her colleague Ivan L. Cameron, PhD, found that simply supplementing the diet of cancer-bearing mice with the type of fatty acids derived from fish increased the effectiveness of three different chemotherapeutic agents: doxorubicin, edelfosine (investigational), and irinotecan (Camptosar).

In the study, mice were fed a standard diet until tumors grew to about 5 mm in diameter. Then the diets were changed to include n-3 fatty acid supplements for 2 weeks before the chemotherapeutic agent was administered. The membranes of all cells quickly incorporated the highly unsaturated fatty acids in the fish oil.

Oxidative Damage

One of the mechanisms of action of most chemotherapy agents is to cause oxidative damage to molecules in cancer cells. Polyunsaturated fatty acids easily oxidize, she said, so increasing the amount of polyunsaturated fatty acids in the cell membranes provides more molecules in the cancer cells that are susceptible to damage by the chemotherapy drugs, and normal cells do not seem to suffer more damage from the chemotherapy.

“We think that the normal cells increase protective antioxidative enzymes during the time the fish oil is being consumed before initiation of cancer chemotherapy, but the cancer cells cannot increase antioxidative enzymes,” Dr. Hardman said. “Thus, we hypothesize that the normal cells are more protected from damage caused by the chemotherapy, but cancer cells are more readily killed.”

The study data support this hypothesis. When fish oil was incorporated into the diet of the chemotherapy-treated mice, normal cells in the liver and colon did not sustain increased damage, but cancers regressed more quickly than in controls getting corn oil supplements.