Researchers might have discovered another new weapon in the fight against cancer -- oxygen.  In a new study in mice, researchers found that something as simple as breathing in extra oxygen might give immune cells the boost they need to attack cancer cells in the body.

The immune system is already known for spotting abnormal cells in the body and destroying them before they grow into cancer.  However, once tumors do take root, they put up defenses designed to block attacks from the immune system.

With the extra oxygen, "you remove the brake pedal" that cancer can put on tumor-fighting immune cells" lead author of the study and director of the New England Inflammation and Tissue Protection Institute at Northeastern University, Michail Sitkovsky says.

According to Edwin Jackson, study co-author from the University of Pittsburgh, tumors can grow so rapidly they outpace their blood supply thereby creating a low oxygen environment.  This lack of oxygen causes the cancer cells to produce a molecule called adenosine.  This molecule essentially puts nearby T cells and the natural killer cells to sleep, preventing them from fighting the cancer.

Researchers wondered if putting oxygen back into the oxygen-starved environment would strip cancer cells of this defense and wake up the sleeping cancer fighting cells.  For the study, they put mice with different kinds of lung tumors inside chambers that mimic what's known as supplemental oxygen therapy.  The air is about 21 percent oxygen, but hospitals can give human patients concentrations of 40 to 60 percent oxygen.

The extra oxygen changed the environment of the tumor and allowed the immune system to wake up and do its job.  The tumors in the mice shrank in the high-oxygen group, especially when researchers combined the oxygen with injections of extra tumor-fighting T cells.  The extra oxygen had no effect in mice genetically engineered to lack those immune cells. 

The study is exciting, says immunologist Susanna Greer of the American Cancer Society, who wasn't involved with the research and cautioned that it must be tested in people.

"If this works, there is the potential that what they're doing could very easily synergize with other cancer immunotherapies that we know work," Greer says.

"The beauty is that oxygen per se is so well-tolerated," added Dr. Holger Eltzschig, an anesthesiologist at the University of Colorado in Denver who studies low-oxygen effects and also wasn't involved in Wednesday's study.

Eltzschig believes that the results from the study was so compelling that researchers should go ahead and begin to test the approach by adding oxygen treatment as a part of certain cancer therapies.