Researchers have found that excessive dietary fat caused a 300 percent increase in the spread of cancer cells in laboratory animals. The image depicts lipid rich cancer cells.
The researchers used an imaging method called coherent anti-Stokes Raman scattering, or CARS, to document how increasing lipids from fat intake induces changes to cancer cell membranes. Those changes, including processes called membrane phase separation and membrane rounding, enhance cancer metastasis.
If the cancer cells don’t have excess lipids they stick together and form very tight junctions in tumors, but increasing lipids causes them to take on a rounded shape and separate from each other. The change in shape is critical to the ability of cancer cells to separate and spread throughout the body via the bloodstream.
The researchers then used another technique, called intravital flow cytometry, to count the number of cancer cells in the bloodstream of the mice. The technique works by shining a laser though the skin and into blood vessels, where the dyed cancer cells are visible.
Results showed the increase in lipids had no impact on the original tumors in the mice. However, the rate of metastasis rose a dramatic 300 percent in the mice fed a high-fat diet.
The researchers later also examined the animals’ lungs and counted the number of cancer cells that had migrated to the lungs as a result of metastasis. Those findings supported the other results showing increased metastasis in animals fed a high-fat diet.
It was also demonstrated that linoleic acid, which is predominant in polyunsaturated fats, caused increasing membrane phase separation, whereas oleic acid, found in monounsaturated fats, did not. Increased membrane phase separation could improve the opportunity of circulating tumor cells to adhere to blood vessel walls and escape to organs far from the original tumor site. The new findings support earlier evidence from other research that consuming high amounts of polyunsaturated fat may increase the risk of cancer spreading.
The findings suggest that combining CARS and intravital flow cytometry represents a possible new diagnostic tool to screen patients for cancer. The tool can be used to count lipid-rich tumor cells circulating in a patient’s blood by shining a laser through the skin and into blood vessels. Because lipids can be detected without the need for dyes, the technique might be developed into a convenient method to diagnose whether a patient’s cancer is spreading aggressively.
It is generally accepted that diet and obesity are accountable for 30 percent of preventable causes of cancer, but nobody really knows why. These findings demonstrate that an increase in lipids leads directly to a rise in cancer metastasis.