The rigours and challenges of spaceflight are remarkably similar to the physical stress cancer patients experiment during chemotherapy and other treatments, according to researchers.
For that reason, the researchers suggest that the countermeasures program used by astronauts before, during and after spaceflight to maintain their health could be developed and applied for cancer patients to help them recover after treatment.
The details were published in a commentary written by researchers from Memorial Sloan Kettering Cancer Center and NASA on Thursday in the journal Cell. The work was supported by the National Cancer Institute.
"It was surprising when we looked at similarities between astronauts during spaceflight and cancer patients during treatment. Both have a decrease in muscle mass, and they have bone demineralization and changes in heart function," said Jessica Scott, senior author and an exercise physiology researcher at the Memorial Sloan Kettering Cancer Center's Exercise Oncology Service. "Astronauts may get something called space fog, where they have trouble focusing or get a little forgetful. That's very similar to what some cancer patients experience, which is called chemo brain."
But astronauts and cancer patients are advised in a completely different way from each other, despite the similar issues they face. The authors of the commentary looked at the countermeasures program created by NASA to see how it might be applied to cancer patients.
For 58 years, NASA has been sending humans into space, with flights ranging from 15 minutes in duration in 1961 to nearly a year on the International Space Station for current astronauts.
The quest for countermeasures to help humans remain stable and healthy in space began early. They didn't know what effect zero gravity might have on the body or specific organs. And they were mainly concerned with cardiac injury, so multiple assessments were used to monitor that activity before, during and after flight, according to the commentary.
NASA's concerns were valid. Apollo astronaut James Irwin had an undetected coronary heart disease and 21 months after returning to Earth, he suffered an acute myocardial infarction, the authors wrote.
Initially, the Project Mercury astronauts, announced in 1959, had to run each day for a month before their spaceflight. Gemini astronauts exercised before their missions and during spaceflight as well, using bungee cords. By the time space station missions began in 2001, NASA had astronauts performing a combination of aerobic exercise and strength training during their 91- to 215-day missions.
Now, in the months prior to their launch, astronauts work with specialists to create a strength, condition and rehab program to create a baseline before flight. They continue the program using equipment on the station. When they return, the astronauts are monitored as they exercise to be sure that their fitness returns to the baseline level established before spaceflight.
After more than 50 years of human spaceflight, researchers know some of the risks posed to the human body by being in zero gravity. Astronauts have to deal with a stressful environment, noise, isolation, disrupted circadian rhythm, radiation exposure and a headward fluid shift that happens when floating as opposed standing on solid ground.
Over time, astronauts staying for six months or more on the station can experience the weakening and loss of bone and muscle atrophy. Astronauts also experience blood volume loss, weakened immune systems and cardiovascular deconditioning since floating takes little effort and the heart doesn't have to work as hard to pump blood, according to NASA's Human Research Program.
The countermeasures were developed to mitigate these risks. But as the authors of the commentary point out, "Cancer is the only major chronic disease condition in which a comparable countermeasures program is not an aspect of...