Omega-3 fatty acids prevent breast cancer from spreading to bones
Omega-3 fatty acids protect against breast cancer. And if you already have breast cancer, they may slow the spread of the disease in the body.
Omega-3 & cancer

A diet with a relatively high amount of omega-3 fatty acids reduces the risk of breast cancer, animal studies and epidemiological studies suggest. And yes, some of those epidemiological studies involve fish oil supplement users.In trials, omega-3 fatty acids seem to make breast cancer chemotherapy more effective, [Br J Cancer. 2009 Dec 15;101(12):1978-85.] and there are even indications that a diet high in omega-3 fatty acids can improve the survival chances of women with breast cancer.
Against this background, the results of the research that French oncologists, affiliated with the University of Tours, published in Nutrients not so long ago will come as no surprise. The researchers studied the fat composition in the breast tissue of 261 women with breast cancer, and then determined whether the tumors had spread to the bones in these women.

If breast cancer spreads to other tissues, then the bones are target number 1. The concentration of omega-3 fatty acids in the adipose tissue gives a good indication of the intake of omega-3 fatty acids over a longer period of time.
In the younger and pre-menopausal women, the researchers found metastases to the bones less often if the women had a relatively high amount of omega-3 fatty acids in their adipose tissue. This may mean that omega-3 fatty acids can slow the spread of the disease in the body.

In the post-menopausal women, the researchers found a trend pointing in the same direction - but this trend was not statistically significant.
"Our retrospective and exploratory study shows that low levels of n-3 LC-PUFA in the adipose tissue of premenopausal women with breast cancer are associated with bone metastasis formation", write the researchers.

"Additional studies in human will be required to determine the origin of these low levels of n-3 LC-PUFA before proposing an n-3 LC-PUFA supplementation to prevent or contain bone metastasis in premenopausal women with breast cancer."
Nutrients. 2020 Dec 15;12(12):3832.