Dr. Jose Russo, director of the Breast Cancer Research Laboratory at Fox Chase Cancer Center, says tamoxifen is a drug that interferes with the activity of the female hormone estrogen and has been used to treat breast cancer and reduce the risk of breast cancer in women who are at increased risk of developing breast cancer.
Russo and a research team led by Dr. Andrea Manni of Pennsylvania State University induced mammary tumors in rats and then divided the animals into four groups. They fed the groups either a 17 percent fish oil diet, with or without tamoxifen, or a 20 percent corn oil diet, with or without tamoxifen, for eight weeks.
The study found omega-3 fatty acids produced a sign of lower cancer severity, compared to corn oil, but the combination of fish oil and tamoxifen reduced the expression of genes linked to tumor growth and spreading of cancer.
"If a tumor was being treated with tamoxifen, the addition of an omega-3 fatty acid diet seemed to make the tumor, at least at the molecular level, more benign and less aggressive and responsive to tamoxifen," Russo says in a statement.
The findings were presented at the American Association for Cancer Research 102nd annual meeting in Orlando, Fla.