Researchers recently discovered that a chemical that is produced in the body when it metabolizes omega-3 fatty acids is a potent inhibitor of angiogenesis, or blood vessel growth. Tumors need massive amounts of nutrients to grow and spread, so they send out signals to the local area that encourage blood vessel growth that supply food to the growing tumor. If this is blocked then the tumor can starve and will have a smaller chance of spreading to the rest of the body.

Omega-3 fatty acids are found in foods such as fish and breast milk and diatery supplements.

"Our investigation opens up a new understanding of the pathways by which omega-3 fatty acids exert their biologic effects," said Guodong Zhang, the lead author of the article and a postdoctoral researcher in the laboratory of Bruce Hammock in the Department of Entomology and the UC Davis Comprehensive Cancer Center.

There are currently next-generation treatments for cancer that use the same theory and block blood vessel growth factors. One such medication is Avastin sold by Genentech/Roche, which is currently used to treat various cancers but can cost over $30,000 a year. These class of drugs are antibodies that block VEGF, a protein that encourages blood vessel growth in wound healing that is also used by tumors.

"It may be possible to improve the efficacy of these anti-cancer drugs by combining them with a diet high in omega-3 and low in omega-6 fatty acids," Dr. Hammock, whose lab the research was produced in, said.

When omega-3 fatty acids are metabolized by the body they turn into a chemical called epoxy docosapentaenoic acid (EDP). In mice with tumors EDP was able to block blood vessel growth and slow down cancerous cells from metastasizing to the rest of the body. Researchers tested the lipid in mice and in cell cultures and saw that tumors shrank and did not spread to other parts of the body as easily as controls.

The FDA currently has approved two drugs which block the breakdown of EDP in the body, sorafenib and regorafenib. "It may be possible to improve the efficacy of these anti-cancer drugs by combining them with a diet high in omega-3 and low in omega-6 fatty acids," Dr. Hammock said.

The research was recently published in the Proceedings of the National Academy of Science.