Will Eating Fish Prevent Breast Cancer?

A new report was published online June 27 in the journal BMJ (British Medical Journal) which claims that regularly eating oily fish such as salmon, tuna or sardines may help reduce the risk of breast cancer.

These fish are known to contain a fatty acid called PUFA’s (n-3 polyunsaturated fatty acids). Twenty one different studies that looked at the intake of fish and PUFAs were reviewed by Dr.Li and his group. More than 800,000 women in the United States, Europe and Asia, and 20,000 cases of breast cancer were included in previously published research. The women were followed from 4 to 20 years.

Conflicting results about the protective effects of PUFAs that are found in fish and breast cancer risk has been identified in earlier research. Dr.Li decided to combine the results of the 21 studies and reanalyze them.

His analysis concluded that women with a high intake of PUFAs had a 14 percent reduction in breast cancer risk. There was a 5 percent lower risk of breast cancer, for every 0.1-gram-per-day increase in the intake of the fatty acids.

According to Dr. Li, “One to two servings of oily fish per person per week is suggested”.

Li agrees he can’t explain that there is a definite association between PUFAs and decreased breast cancer risk. He said that one possibility is that the fatty acids may help regulate the activities of molecules involved in cell growth and in the spread of cancer cells.

Two experts from the US who reviewed the new findings describe the pros and cons to the report. Dr. Stephanie Bernick (Chief of Oncologic Surgery at Lenox Hill Hospital in NY city) said, the link found between fatty acid intake and breast cancer risk reduction “is not necessarily cause-and-effect.”

Dr. Joanne Mortimer, director of women’s cancer programs at the City of Hope Comprehensive Cancer Center in Duarte, Calif., agreed. “My take on this is it may be more than just what they eat” that helps reduce breast cancer risk, she said. “To make an assumption that the lower risk is due entirely to diet may be a false one.”

Dr. Mortimer said, the women with a high dietary intake of PUFAs may have healthier lifestyle habits in general and also may be more apt to exercise and follow better diets.
It’s no cure-all,” Bernik said. And, if eaten in excess, the mercury content of some fish can be unhealthy, she added.

Source: Duo Li, Ph.D., M.Sc., professor, nutrition, Zhejiang University, Hangzhou, China; Joanne Mortimer, M.D., director, women’s cancer programs, City of Hope Comprehensive Cancer Center, Duarte, Calif.; Stephanie Bernik, M.D., chief, surgical oncology, Lenox Hill Hospital, New York City; July 27, 2013, BMJ, online

Many studies on cancer prevention hit the press and here is another one to add to the list. As with all newly published data, it is wise to wait until the evidence has been reviewed and tested again before accepting the results as fact.