Radiation makes even healthy breast tissue cancerous.

1902 MAR 28 - (NewsRx.com & NewsRx.net) -- New experimental findings show that exposure to ionizing radiation creates a microenvironment in the tissue surrounding breast cells that can cause even nonirradiated cells and their progeny to become cancerous.

The discovery suggests new and possibly more effective means for preventing breast cancer. It was made by Lawrence Berkeley National Laboratory (Berkeley Lab) cell biologist Mary Helen Barcellos-Hoff.

Speaking in Boston, Massachusetts at the annual meeting of the American Association for the Advancement of Science (AAAS), Barcellos-Hoff described her study in which a special line of nonirradiated, nonmalignant breast cells were transplanted into irradiated mammary glands.

Nearly 75% of the transplanted glands developed tumors, and the effect persisted up to 14 days after the radiation exposure.

Tumors developed in fewer than 20% of the glands when Barcellos-Hoff transplanted the same type of cells into nonirradiated mice.

"Our studies demonstrate that radiation elicits rapid and persistent global alterations in the mammary gland microenvironment," said Barcellos-Hoff. "We believe that these radiation-induced microenvironments lead to changes in the physical characteristics (phenotypes) of cells and their progeny that promote carcinogenesis. In other words, radiation exposure can cause breast cancer by pathways other than genetic mutations."

Studies by Barcellos-Hoff and her research group indicate that one of these alternative pathways is damage to the tissue that surrounds a breast cell. This surrounding tissue, which includes a network of fibrous and globular proteins called the extracellular matrix (ECM), normally acts to suppress cells from becoming cancerous.