Boosting oxygen in the air helped mice with cancer battle lung and breast tumors. Normal air contains 21 percent oxygen. Raising oxygen concentrations to 60 percent energized immune cells to shrink tumors in mice, researchers report in the March 4 Science Translational Medicine.
About 40 percent of cancer-ridden mice put in an oxygen-rich environment survived 60 days or more. In contrast, mice that breathed normal air after getting an injection of lung-cancer cells died within about 30 days, say Stephen Hatfield of Northeastern University in Boston and colleagues.
Tumors grow rapidly as they suck up all the oxygen around them. Low oxygen causes tumors to release a chemical called adenosine, which makes immune cells sluggish and promotes tumor growth. Boosting oxygen counteracts adenosine and perks up immune cells called T cells and natural killer cells that shrink tumors, the researchers found.
A little extra oxygen may boost the effectiveness of immune therapies already being given to cancer patients, the researchers say. Too much oxygen can be toxic, though. And previous studies of people and animals have produced mixed results about the relationship between oxygen and cancer