Antioxidants aid cancer cells in metastasizing, research shows

Antioxidants may help some cancer cells spread throughout the body and establish new tumors, according to new research from an oncology research group at the University of Texas Southwestern.

Antioxidants, some of which are vitamins, play a key role in the removal of free radicals from cells in the body. Free radicals can cause cell damage and death when left unchecked. Many people advocate taking antioxidants orally to help prevent a number of diseases, such as cardiovascular diseases like heart attacks or strokes, along with some forms of cancer and other diseases. But the evidence that antioxidants are good at preventing these diseases or in helping people recover from them is limited.

The Texas Southwestern researchers used mice that they had injected with human melanoma cells. Melanoma is a virulent form of cancer that can develop in the skin. The original skin tumor is less of a problem than the metastases — the cells from the tumor that break off and enter the bloodstream — moving to a new site like the brain or liver. The metastases, as they grow, are often responsible for the death of the patient.

Science via Shutterstock

Science via Shutterstock

Fortunately, metastasis is not easily accomplished.  Once the malignant cell leaves the tumor it undergoes attack from the immune system. In the vast majority of cases, the attack is successful and the malignant cell dies. But over time, more and more cells attempt to metastasize and finally some do manage to do so successfully, setting up tumors elsewhere.

One mechanism that seems to help destroy these migrating tumor cells is called “oxidative stress.” In this process some types of oxygen species interfere with the normal cell metabolism. Free radicals get produced and aren’t removed.  The cell experiences more and more damage and eventually dies. Antioxidants limit oxidative stress. So having antioxidants present in the system can actually help to protect the tumor cells that break off and float along in the blood.

This was confirmed by researches when they implanted the human melanoma cells in the test mice.  The untreated mice died as their melanomas spread.  Mice treated with an antioxidant had more metastases and died earlier than the untreated control mice.  So it appears that the antioxidants benefitted the cancer cells in this case, more so than normal cells — at least with these melanoma cells. Additional research will need to be done to see if antioxidants will also protect other types of metastatic cancer cells.  Of course, further research needs to be done on this problem.

Perhaps in future studies, melanomas can be treated with pro-oxidants that would increase their oxidative stress levels and work to kill off more, perhaps all, metastatic cells.


Mark Thoma, MD, is a physician who did his residency in internal medicine. Mark has a long history of social activism, and was an early technogeek, and science junkie, after evolving through his nerd phase. Favorite quote: “The most exciting phrase to hear in science... is not 'Eureka!' (I found it!) but 'That's funny.'” - Isaac Asimov

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