Saraswoti Khadge, a Ph.D. student in the laboratory of James Talmadge, Ph.D., professor, pathology and microbiology and director of the UNMC Laboratory of Transplantation Immunology, was the lead author on the study. Starting in October, Khadge has accepted a research position at Vanderbilt University.
Khadge noted that fatty acids stopped further tumors from forming and blocked the cancerous cells from spreading to other organs in mice. She speculates that this might be because of the way in which omega-3 fatty acids support the body’s immune and anti-inflammatory system.
"The studies by Khadge provided insight not only on the impact of dietary omega-3 fatty acids on tumor growth and metastasis but also on the sites of metastasis," Dr. Talmadge said. "Thus, not only were common metastasis sites reduced but also secondary tumor growth in the ovaries, kidneys and contralateral breasts."
Two groups of adult female mice were fed an almost identical liquid diet. The calorie count and percentage of fat that each contained were the same. The notable difference was that one diet contained olive oil rich in omega-6 polyunsaturated fats, and the other diet contained fish oil rich in omega-3 fatty acids.
The mice were then injected with 4T1 breast cancer cells that cause aggressive tumors to develop in breast glands. These cells are known to spontaneously spread to other parts of the body, such as bones, the lungs and liver, but less frequently to the heart, kidneys and ovaries. The mice were autopsied and studied 35 days after the breast cancer cells were injected.
Khadge and her colleagues found the chance that the breast cancer cells would take hold in the breast glands of the adult female mice was significantly lower in those put on the omega 3-diet. Tumors took significantly longer to start developing in these mice, and therefore had an influence on their size.
After 35 days, the tumors detected in their breast glands 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, and these mice survived longer than those on the omega-6 diet.
More T-cells were found in the tissue of the mice in the omega-3 group than in the omega-6 group, Khadge said. This is important because T-cells are white blood cells that play a role in strengthening the immune system, and curbing inflammation. Khadge said this could mean that a diet rich in omega-3 fatty acids helps to suppress the type of inflammation that can trigger the rapid development and spread of tumors.
"Our study emphasizes the potential therapeutic role of dietary long-chain omega-3 fatty acids in the control of tumor growth and metastasis," said Khadge, who emphasizes that this does not mean that an omega-3 diet could summarily prevent breast cancer tumors from forming altogether.
This study is based on dietary consumption during adult life. Its findings are in line with previous cell studies that showed how eating fish oil-based diets during pregnancy and as a child markedly suppresses the development and spread of breast cancer.
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