Pure oxygen seen as cancer cell inhibitor

Long Island doctors are asking an unusual question in the ongoing fight against the deadliest form of brain cancer -- whether exposing patients to pure oxygen in a pressurized chamber will help boost chances of long-term survival.

An experimental treatment -- the only one of its kind in the United States -- is being tested at Winthrop University Hospital in Mineola, drawing upon a deceptively simple theory: Brain tumor cells weaken in the presence of pure oxygen.

Weakened tumors, doctors say, might be more vulnerable to standard cancer therapy.

Drs. Paul Duic and Jai Grewal are working with a team of Winthrop investigators trying to determine if spending about an hour in a hyperbaric oxygen chamber immediately before undergoing radiation therapy renders tumors more amenable to destruction.

The chamber is a cylindrical vessel in which the patient remains enclosed while a specialist in hyperbaric medicine adjusts the chamber's internal environment, delivering oxygen at a level higher than atmospheric pressure.

By simply inhaling pure oxygen, patients force more oxygen into the brain, theoretically allowing radiation treatments to be more effective, doctors say.

Radiation therapy has to be performed within 15 minutes of pure oxygen exposure.

"We've known for years that radiation delivered under aerobic [oxygenated] conditions has a threefold increase in efficacy," said Duic, co-director of the Long Island Brain Tumor Center at Neurological Surgery, a practice in Rockville Centre.

Duic, a neuro-oncologist, is leading the investigation that so far involves about 25 Long Island patients. The hope, he said, is to expand the research beyond Long Island into a national clinical trial. Patients also will undergo standard chemotherapy.

Doctors are treating patients diagnosed with glioblastoma, the most common and aggressive form of brain cancer. Only 26 percent of patients are alive two years after diagnosis.

Hyperbaric oxygen therapy for malignant brain cancer was first tested at Columbia University in the 1970s, but the research was abandoned as newer forms of chemotherapy became available. Recent studies in Japan have revealed that treating patients with hyperbaric oxygen before radiation treatment resulted in longer survival.

Winthrop's research, which is just beginning, is expected to run through next year.

Grewal, a neuro-oncologist, noted that glioblastomas proliferate by preventing oxygen from entering tumor cells. Healthy brain cells, by contrast, crave oxygen and thrive on it.

"We know that these brain tumors prefer a low-oxygen metabolic state, and there is evidence that this metabolic state may contribute to the tumors' ability to resist the effects of radiation and chemotherapy," said Grewal, also a co-director of the Long Island Brain Tumor Center.