Oct. 16 (UPI) -- A diet that contains healthy doses of omega-3 fatty acids, found in fish oil, may help control the growth and spread of breast cancer cells, according to a study with mice.
The fatty acids stopped additional delayed tumors from forming and blocked cancerous cells from spreading to other organs in mice, researchers report. The new findings were published Tuesday in the journal Clinical & Experimental Metastasis.
"Our study emphasizes the potential therapeutic role of dietary long-chain omega-3 fatty acids in the control of tumor growth and metastasis," Dr. Saraswoti Khadge, of the University of Nebraska Medical Center, said in a press release.
The American Heart Association recommends adults consume fish twice a week to gain omega-3 fatty acids to help reduce risk of congestive heart failure, coronary heart disease, sudden cardiac arrest and ischemic stroke, though it also advises against supplements with the oil because of a lack of health benefits.
The new cancer study was conducted with mice, but previous research has shown that consuming fish oil, including in capsule form, during pregnancy and as a child markedly suppresses the development and spread of breast cancer.
Khade emphasized that the new findings do not mean an omega-3 diet could summarily prevent breast cancer tumors from forming altogether. But Khade and his colleagues believe these omega-3 fatty acids support the body's immune and anti-inflammatory systems.
In the study, two groups of 20 adult female mice were fed a liquid diet with similar calorie count and percentage of fat. But one diet contained plant oils rich in omega-6 polyunsaturated fats and the other diet contained fish oil rich in omega-3 fatty acids.
Then, the mice were injected with 4T1 breast cancer cells, which are known to cause aggressive tumors in the breast and to spread elsewhere.
The mice were studied in autopsies 35 days after the breast cancer cells were injected.
Among mice injected with the omega-3 fatty acids, tumors took significantly longer to start developing and the omega-3 dose helped affect tumor size -- the tumors detected in their breasts were 50 percent smaller than those that developed in the omega 6-group.
The likelihood of the cancerous cells growing and spreading to other organs in the omega-3 group was also lower, omega-3 mice survived longer than those on the omega-6 diet and some of the omega-3 fed mice appeared to never develop breast cancer.
More T-cells -- the white blood cells that play a role in strengthening the immune system against tumors -- were found in the tissue of the mice in the omega-3 group than in the omega-6 group. Mice injected with omega-3 diet also had less inflammation.
Researchers believe inflammation can trigger the rapid development and spread of tumors, as well as promote T-cell responses to tumors.