Wed Jul 12, 7:09 PM ET

WEDNESDAY, July 12 (HealthDay News) — Mice that received a single therapeutic dose of radiation — comparable to a single dose of radiation received by human cancer patients — lost as much as 39 percent of the spongy portion of their inner bone, researchers report.

That loss reduced the inner bone’s weight-bearing connections by up to 64 percent, the research team added.

While the results of this mouse study cannot be directly applied to humans, it does raise potential concerns about cancer patients receiving radiation therapy and radiation exposure for astronauts on long space flights, the researchers noted.

“We were really surprised at the extent of bone loss,” lead researcher Ted A. Bateman, a Clemson University bioengineer who studies bone biomechanics, said in a prepared statement. “We’re seeing bone loss at much lower doses of radiation than we expected.”

His team published the findings online in the Journal of Applied Physiology.

The mice in the study received a single 2 Gray (Gy) dose, which is comparable to the single 1-2 Gy dose received by cancer patients, who receive a series of doses over the course of their treatment, for a total of between 10 to 70 Gy.

The mice suffered a loss of trabecular bone, the spongy area of bone inside the dense outer cortical bone.

“It’s interesting that the trabecular bone, not the cortical bone, suffered the damage,” Bateman said.

The loss of spongy bone results in a less efficient bone support structure, making the bone more susceptible to fractures, the researchers said.