Space travel for long periods can cause cancer

In a finding that could have major consequences for staying in space for long periods, a new study has suggested that astronauts undertaking long-duration space travel could be at increased risk of colon cancer and premature aging.

Researchers at Georgetown University Medical Center, the United States, blames this negative fallout of long-duration space travel on high-energy radiation present in space.

The finding has huge implications for the long-term travel in space that is needed for Project Constellation, the program launched by United States’ National Aeronautics and Space Administration (NASA) to return humans to the Moon and then on to Mars.

The newspaper Washington Post quoted Kamal Datta, author of the study and assistant professor at the Lombardi Comprehensive Cancer Center at Georgetown University Medical Center, as saying in a statement, “Radiation exposure, either intentional or accidental, is inevitable during our lifetimes. 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."

In the study, researchers who exposed mice to the high linear energy transfer (LET) radiation similar to that found in space found that it created a highly oxidative cellular environment in the gastrointestinal tract over prolonged periods of time, a condition favorable for development of cancer.

The earth’s atmosphere blocks much of high-LET radiation – which is found in solar flares – from reaching the Earth.

According to Kamal Datta and colleagues, the radiation produced free radicals that damage the DNA in a cell. Over a period of time, accumulated damage can result in mutations and, in some cases, malignant tumors.

It was also noticed that the cell’s stress response to the free radical damage continued up to two months after exposure to the high-LET radiation.

The mice exposed to the high-LET radiation aged prematurely, researchers said in the statement, adding that their fur became prematurely gray.

This is not the first time that the possible association between space travel and cancer has been revealed, according to the report in the Washington Pos. In 2004, the National Academies, of the United States, reported it had found that “the frequency of cancer in the astronaut population was higher than the incidence among the general population in the United States.”

The study by the Lombardi Comprehensive Cancer Center at Georgetown University Medical Center was presented at a convention of the Association for Cancer Research held in San Diego, California, from April 12-16, 2008.