Scientists study using low-dose radiation – Philly.com.

By Marie McCullough, Inquirer Staff Writer

POSTED: September 08, 2013

In very rare cases, using radiation to kill the primary tumor of a patient with metastatic cancer leads to the disappearance of tumors throughout the body.

Scientists can’t explain this amazing collateral effect, but it seems to activate an antitumor immune response.

Mohan Doss, a medical physicist at Fox Chase Cancer Center, believes the distant tumors melt away because of incidental low-dose rays emanating from the high-dose therapy. And that bolsters a theory he has researched for years: radiation at or slightly above natural background levels can stimulate the body’s disease-fighting defenses.

“When you have high-dose radiation, it suppresses the immune system,” he said. “Low doses actually enhance the immune system.”