TUESDAY, April 15 (HealthDay News) -- Astronauts may be at
increased risk of colon cancer and premature aging from the
high-energy radiation found in space, a new report says.
The study, expected to be presented Tuesday during the American
Association for Cancer Research annual meeting in San Diego, has
implications for the long-term space travel necessary for Project
Constellation, the recently launched NASA program to return humans
to the moon and then on to Mars.
"Radiation exposure, either intentional or accidental, is
inevitable during our lifetimes," study author Kamal Datta, an
assistant professor at the Lombardi Comprehensive Cancer Center at
Georgetown University Medical Center, said in a prepared statement.
"But with plans for a mission to Mars, we need to understand more
about the nature of radiation in space. There is currently no
conclusive information for estimating the risk that astronauts may
experience."
Researchers exposed mice to the high linear energy transfer
(LET) radiation similar to that found in space. They found that it
created a highly oxidative cellular environment in the
gastrointestinal tract over prolonged periods of time, a condition
favorable for cancer development.
High-LET radiation is found in solar flares. The earth's
atmosphere blocks much of this radiation from reaching us.
The radiation produced free radicals that damage a cell's DNA.
Over time, accumulated damage can lead to mutations -- and, in some
cases, malignant tumors. Datta and colleagues also noted the cell's
stress response to the free radical damage continued up to two
months after exposure to the high-LET radiation.
Also, the mice exposed to the high-LET radiation aged
prematurely, researchers said. Datta said their fur became
prematurely gray, an observation the team plans to follow-up with
MRI brain scans.
This is not the first possible link between space travel and
cancer. The National Academies reported in 2004 that it had found
the frequency of cancer in the astronaut population was higher than
the incidence among the general U.S. population.
More information
The American Association of Retired Persons has more about
how free radicals affect the body.
