Before astronaut Scott Kelly departed on a one-year mission to the International Space Station in 2018, he asked NASA a brilliant question: Would the agency want to compare his pre- and post-spaceflight cellular health with his identical twin brother Mark’s, who would remain on Earth?
NASA leapt at the opportunity, launching the Twins Study – and with it, a new frontier in cancer radiation research.
Striking similarities surfaced between the journeys of patients with cancer and astronauts on space missions. Along with the need for safer radiation guidelines, both face physical and emotional challenges that are difficult to replicate.
As such, my research colleagues and I are collaborating with NASA to work toward not only safer long-term space travel – the Twins Study is seen as a stepping-stone to a three-year mission to Mars – but also improvements in future standards of care in radiation therapy.
How interstellar radiation compares with cancer therapy
The Van Allen radiation belts – two looping magnetic fields – surround the earth, blocking radiation from affecting us on the ground. But when astronauts leave earth’s orbit (a feat known as LEO) they are more vulnerable to interstellar radiation.
While the space station provides partial protection, astronauts are subjected to low doses of radiation daily during missions, along with occasional solar flares that deliver higher doses of radiation instantly.
Watch this: SDO Spots X8.2-Class Solar Flare, Sept. 10, 2017
NASA is concerned with the potentially negative ramifications of radiation exposure on astronauts’ health during long-term missions. Paired with many other challenges of prolonged space travel, from low-gravity to an expanse of technical functions their lives depend on, astronauts’ bodies and minds are taxed during space journeys.
"Striking similarities surfaced between the journeys of patients with cancer and astronauts on space missions. Along with the need for safer radiation guidelines, both face physical and emotional challenges that are difficult to replicate."
As we’ve learned more about cancer processes in the last decade, radiation therapy has advanced by leaps and bounds. Traditional radiotherapy took a “spray and pray” approach – doctors irradiated the tumor plus the healthy tissue within a specific radius with the goal of preventing recurrence. Unfortunately, this technique resulted in unnecessary tissue damage, skin changes, and inability to radiate the area again should the cancer return.
Today’s stereotactic radiation techniques, such as CyberKnife and Gamma Knife, allow doctors to focus radiation precisely on a tumor, sparing more healthy tissue and reducing treatment side effects. Still, there is always room for improvement, particularly in treating a disease as innately destructive as cancer.
Striking similarities between spaceflight and cancer treatment
Not unlike the extremes of space travel, patients with cancer undergo challenges that other people might not fully understand. Cancer mangles cellular health, growing until the tumor metastasizes, or spreads, and disrupts body functions.
Along with the need to limit radiation exposure, there are four other correlative experiences between astronauts roaming the recesses of space and patients managing cancer treatment:
- Emphasis on general wellness: NASA’s space program is incredibly competitive, and astronauts are required to meet stringent health qualifications. They are typically in superior physical condition. Related, the bulk of research shows that eating a healthy diet and exercising regularly can reduce the risk of more than 10 types of cancer, along with making cancer treatment more bearable.
- Encumbered movement: In space, low or zero gravity reduces the load on the limbs and astronauts are at risk of losing substantial muscle tone during a long mission. They’re prescribed isometric exercises to maintain cardiac and general fitness. On Earth, patients with cancer often lose weight, including muscle tone and fitness, particularly during treatment for late-stage cancer.
- Isolation: Space flight crews are often small teams or just one individual. When not communicating with NASA personnel on the ground, they can feel isolated, as if no one else really understands what they’re going through – much like patients with cancer.
- Stress: Life on a space station can be stressful for all the reasons mentioned above, as well as the vast unknowns in space. Similarly, patients must face the unpredictability of their disease, and all the unknowns that come with it.
Using these findings, along with the results of the NASA Twins Study, we are working toward improving preventive measures and reducing radiation side effects.
Related reading: Radiation Oncology Patient Resources
Cancer-related results from the NASA Twins Study
In the Twins Study, NASA found that Scott Kelly’s immune responses were not affected by spaceflight, including the T-cell receptor repertoire, an important physiological factor in cancer treatment and survival. Several other biological functions were temporarily impacted, including cognitive function, gut microbiome composition, the dimensions of Kelly’s arteries, and changes in his retinas.
Most fascinating, however, was what happened to Scott Kelly’s DNA. Even after six months back on Earth, his gene expression levels were still below baseline, and damage to his chromosomes actually increased. NASA issued a statement confirming that Scott and Mark Kelly remained identical twins despite the minimal changes in Scott’s gene expression, and that it did not fundamentally alter his DNA.
It would be easy to take these data at face value and suggest that prolonged space travel is wildly unsafe and not sustainable long term. However, like NASA researchers, I am optimistic this data can help us not only improve the safety of space travel but also develop new approaches to administering radiation to patients with cancer and reducing side effects.
My colleagues and I are currently working with NASA to determine how to reduce the risk of radiation-induced lung and colon cancer because, according to our research, astronauts are at a higher risk for those forms of cancer.
Twice or three times a year, UT Southwestern researchers travel to Brookhaven National Laboratory, a NASA research facility, which is the only place in the U.S. in which we can partially simulate a space radiation environment. There, we are testing a countermeasure formulation, which is comprised of antioxidant and anti-inflammatory compounds, on laboratory mice that have been genetically modified to be susceptible for lung and colon cancer.
We found that when we feed the mice the countermeasure three days before radiation, their risk of fatal cancers is dramatically reduced. Additionally, our research indicates that the countermeasure only protects healthy tissue, not cancer cells. This research could have huge implications on earth as well as in space.
Our hope is that the countermeasure will be approved for human trials as an oral medication by the end of 2019. I am on the Scientific Advisory Board of a company, Reata Pharmaceuticals (Irving, Texas), that is in advanced clinical trials testing this agent.
A few closing thoughts
NASA equips the space shuttle’s key technology with triple redundancies – backups for backups. Unfortunately, we can’t do that with humans. The best we can do is to try to prevent cancer before it develops, catch it early if it does, and continue advancing therapies and treatments for patients.
Collaborating on research like the Twins Study can have important, real-life implications for cancer therapy. When people complain that spending time and money on space missions and research is wasteful, I look at the patients who travel to UT Southwestern and other cancer centers specifically to get cutting-edge treatment.
Astronauts live to be 92 on average. Thousands of them have gone into space, and when they retire, they resume a typical lifestyle. Data shows their long-term risk of cancer is no different than anyone else after some time spent earthbound. And they live a long time, which tells me NASA is onto something we have yet to unravel.
If we can translate more of NASA’s findings into actionable cancer prevention and treatment, that’s enough validation for me that the work we’re doing is resoundingly important.
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