Experts in oncology help advise NASA on space radiation health standard for astronauts
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A select group of people who spend their day jobs fighting cancer — as surgical oncologists, radiation epidemiologists, or working in radiobiology and bionanotechnology — had a unique opportunity to lend their expertise to NASA.
The Committee on Assessment of Strategies for Managing Cancer Risks Associated with Radiation Exposure During Crewed Space Missions included several experts from the field of oncology among its 18 members. Their task was to give advice on proposed NASA updates to the space radiation health standard that establishes the allowable limit of radiation exposure by astronauts during their careers.
“This was timely for a couple of reasons,” Robert L. Satcher, MD, PhD, associate professor in the department of orthopedic oncology at The University of Texas MD Anderson Cancer Center, told Healio | HemOnc Today.
“One is the return to deep space exploration. With plans to send people to the moon and to Mars, what are the additional risks of that?” Satcher said. “In addition, the radiation health standards were established about 30 years ago based primarily on World War II data from Japan, after the atomic bombs. More data have been accumulated over the years, so it was time to look at those data and see how they affect recommendations going forward.”
Committee members with connections to oncology viewed their contributions to the conversation as both an important responsibility and a privilege.
“For many of the committees I've been on, the question is, ‘What research do we need to do now to solve this problem so we're ready to go to Mars in 10 or 15 years?’” Carol Scott-Conner, MD, PhD, MBA, emeritus professor of surgery in surgical oncology and endocrine surgery at Carver College of Medicine at University of Iowa, told Healio | HemOnc Today. “What are the important questions? You're trying to think ahead. I would have loved to fly in space, but this is the next best thing.”
Healio | HemOnc Today spoke with members of the committee about the opportunity to apply what they’ve learned in oncology to expand space travel and ensure the safety of NASA astronauts.
‘An amazing opportunity’
Many members of the committee were not new to working with NASA.
About 10 years ago, Amy Berrington de González, DPhil, senior investigator and chief of the radiation epidemiology branch at NCI, accepted a role on a National Academies of Sciences, Engineering, and Medicine committee that reviewed NASA’s radiation risk model.
“It’s fascinating,” Berrington de González told Healio | HemOnc Today. “It was just such an unusual idea to think about what we know about medical radiation exposure, how it might help decide how long astronauts can stay in space, and whether or not they can fly to Mars safely. It’s an amazing opportunity.”
Each member of the cancer risk assessment panel, assembled earlier this year as an ad hoc committee of the National Academies, brought a very specific set of skills. Some were worked in radiation protection, others in radiation biology dosimetry, aerospace medicine, biostatistics, ethics, communication or risk management.
Berrington de González, a leading expert in cancer epidemiology, has studied cancer risks from medical radiation exposures, including working on the first epidemiological study supporting a direct link between CT scans and subsequent cancer risk. She was tasked with helping project radiation risk estimates within space travel beyond the Van Allen radiation belt.
“You have someone like me, who knows how to project radiation risk estimates from terrestrial radiation — usually from medical exposures, but essentially any kind of terrestrial radiation — and then you have to bring in the radiobiology of the space radiation, since we don’t have the direct observations. You bring those two parts together in the model to try to project what we think the risks are,” she said.
Berrington de González said there are obvious uncertainties and paraphrased a quote from former U.S. Defense Secretary Donald Rumsfeld (which Rumsfeld, coincidentally, has credited to former NASA scientist William Graham) in explaining the science.
“There are the known knowns, the known unknowns and the unknown unknowns. When we put together these risk models, we can model the known knowns and put some modeling parameters into the known unknowns, but we’re always left with the unknown unknowns,” Berrington de González said. “You have to admit that they could be there and you can’t deal with them. That’s one of the reasons we had statisticians in the group, who made sure some of those uncertainties are captured formerly in the risk assessment process.”
The old radiation standards, which had been in place since 1989, were most restrictive for women. They limited career radiation exposure to no more than 3% risk for exposure-induced death for cancer mortality based on a 95% confidence level. Under this standard, a male astronaut would reach his career exposure limit with a 211-day mission to the International Space Station compared with a 43-day mission for a female astronaut, according to highlights of the committee’s consensus study report.
The committee recommended NASA proceed with its plan to implement a single, dose-based limit of 600 millisieverts, calculated by applying NASA’s cancer risk model to an individual who would be most susceptible (ie, a woman aged 35 years).
“This dose limit should apply to all astronauts, regardless of gender and age, which would help promote equal opportunity for mission assignment and for participation in longer spaceflights,” the National Academies wrote in a press release.
Berrington de González said the deliberations were not easy, involving many extra hours in weekend meetings and lengthy debates, but the time and efforts were crucial because no one person could answer the complex questions at hand.
“We all had to work together to understand the many different layers to that kind of decision making, the occupational health perspective, the bioethics perspective, the risk communication perspective, as well as the space radiation and terrestrial radiation,” Berrington de González said.
Helping to ensure the safety and health of astronauts brought forth a “great sense of responsibility” among committee members, she said. But it was a challenge they enjoyed as a change of pace.
“We increasingly spend so much of our time in our hyperspecialized silos. These types of National Academy activities bring people together from a really broad range of expertise, top people in their fields,” Berrington de González said. “I think any opportunities to get out and interact, not only with other scientists, but social scientists and people from really different backgrounds, is always worthwhile. You never know what you’re going to learn and how they can change your perspective on things, as well.”
‘You feel like it makes a difference’
Gayle E. Woloschak, PhD, associate dean for graduate student and postdoctoral affairs and professor of radiation oncology and radiology at Feinberg School of Medicine at Northwestern University, has shared her expertise in a variety of roles over more than 2 decades.
Woloschak has worked at Argonne National Laboratory and advocated at congressional hearings for continued low-dose radiation research funding, and she represents the United States on the United Nations Scientific Committee on the Effects of Atomic Radiation.
She has also served on National Academies committees for NASA for the last 20 years.
“I don’t think I would have dreamt it,” Woloschak said. “It’s one of those things you don’t expect as a biologist, but then again, I never expected to go into radiation biology when I was younger.”
She said she is grateful for the opportunity to take what she’s learned and apply it to helping advance space travel.
“NASA does a lot of their own work on their own standards. But then they try to get an outside panel and say, ‘Listen, this is a nut we can’t crack, and we want some outside advice on it,’ or, ‘This is the way we’re thinking about doing it, but we want to make sure that the broad community agrees that this is the best thing to do,’” Woloschak said. “They were really in a quandary about what to with differences in radiation risk, so they pulled together a panel, an unbiased group. And you know, you feel like it makes a difference.”
Assessing space radiation and cancer risk in space without a real-world sample size isn’t easy. But NASA has a facility in New York — the NASA Space Radiation Laboratory at Brookhaven National Laboratory — that uses beams of heavy ions to simulate space radiation and study biological effects.
“Space radiation is different than the kind of radiation we’re exposed to on Earth,” Woloschak said. “And most of the astronauts, except for those who have gone to the moon, have mostly been within the Van Allen belts, which are what protect us from radiation here on Earth. So, they’ve had some protection from that space radiation.
Dosimeters, such as those set up on Mars, have provided insight into space radiation, Woloschak said.
“We have good estimates of what the radiation is made of and what the radiation looks like and what the does are likely to be,” she said. “But, they are going to be a very different quality than we’re used to.”
Travel to the International Space Station does not expose astronauts to a high dose of space radiation, Woloschak added, and it doesn’t help quantify the radiation one would be exposed to in a further (in distance) and longer (in time) expeditions to Mars.
“That’s where the biologists come in, and what we need to do is test animals that have been exposed to space radiation,” Woloschak said of the facility at Brookhaven, where most of the testing involves mice. “You expose animals to that radiation and then you try to estimate what you’d find in people. And then we take populations like the Japanese atomic bomb survivors and others. Although that radiation isn’t the same as space radiation, we can at least try to understand how that extrapolates from animals to humans, and then do the same thing with space radiation.”
Woloschak echoed Berrington de González in explaining that there are uncertainties involved in such estimates and projections. But the point of assembling a diverse committee is to cover all of the bases in formulating recommendations, she said.
“It’s very interdisciplinary ... there are a lot of things you need to take into consideration,” Woloschak said.
It’s also an experience Woloschak thoroughly enjoys.
“It’s really cool,” Woloschak told Healio | HemOnc Today. “I went down to Houston and visited their radiation facilities. They have a mock-up of the International Space Station. We have astronauts on a lot of our committees. How often do you get to talk to an astronaut about their experiences? Certainly not every day.”
‘An experience-based perspective’
One astronaut with whom committee members spoke regularly has a unique resume for trying to marry the science of space exploration with the experience of treating cancer and assessing its risks.
In between his former job as a musculoskeletal oncologist at Northwestern Memorial Hospital in Chicago and his current role in orthopedic oncology at MD Anderson, Satcher served as a NASA astronaut. In 2009, he became the first orthopedic surgeon in space.
“It was a tremendous experience,” Satcher said.
As with Woloschak and Berrington de González, Satcher had previous committee service under his belt. A few years ago, he worked with a group that assessed the effects of microgravity on musculoskeletal system.
On the most recent committee, Satcher’s experience traveling in space was highly valued. Satcher and Bernard A. Harris Jr. were the two former astronauts on the 18-person committee.
“When NASA is trying to figure out what its approaches should be ... they turn to the scientific community and the medical community for advice, and that's what these committees are for,” Satcher said. “They also want voices of astronauts on those committees to provide an experience-based perspective. I think it's very important because a lot of the recommendations may be translated into policies. And the most precious asset is the astronauts.”
Work on such National Academies’ committees is “very rewarding” for someone who has always had a thirst for knowledge, Satcher said.
“These advisory committees are very educational and informative,” he said. “I've always come away from them having learned something.”
Working on a committee specifically assembled with experts from a variety of disciplines was a refreshing change, too.
“When I go to research conferences, it’s a bunch of people focused on very specific research problems, and when you go to clinical conferences it’s the same,” Satcher said. “It's obviously enjoyable ... but it's a pretty narrow focus. And it doesn't give you that sort of interdisciplinary and global perspective. The nice thing about these committees is you're bringing together people from different corners, not only people on the clinical side and/or the research side or within hardcore sciences, but also communications experts, ethics policy people. It really gives you that bigger picture. Even when I go back to my everyday work, having that kind of experience definitely influences the way that I look at things.”
The consensus study report that committee members presented to NASA recommended the agency “provide all astronauts with an individual risk assessment when communicating about the radiation health standard” and “communicate a comprehensive picture of an individual astronaut’s cancer risks, to place the radiation exposure-induced risk in context.”
Satcher said that recommendation was essential.
“There's a lot of technical sophistication among astronauts and sometimes that gets taken for granted,” Satcher said. “I think part of the emphasis was to be a little bit more proactive in involving astronauts and making sure communications were optimized. It brings it more in line with how we practice medicine. We have to communicate some pretty sophisticated concepts in the cancer world to people who aren't as technically proficient as your average astronaut. It was encouraging to see that change.”
Offering a ‘generalist’ view
Scott-Conner has been working with the National Academies as an advisor to NASA for more than 20 years, beginning when she got a phone call from a former professor. He asked if she knew any surgeons who could serve in an advisory capacity for issues related to astronaut health. She rattled off a handful of names, but none could be considered since they were getting funding from NASA.
“Well, if you can’t come up with anyone else,” Scott-Conner responded, “I’d be interested in doing it.”
Already decades into a distinguished medical career — she became the second woman in U.S. history to serve as head of a department of surgery when she was hired at University of Iowa in 1995 — Scott-Conner worked on “Safe passage: Astronaut care for space exploration missions” in her first National Academies committee role and has continued to share her expertise on other panels.
“It’s making sure that they have the best information and they’ve considered all the possible avenues of research that might be helpful,” Scott-Conner said. “It definitely has a real cool factor to it. It’s been fascinating.”
The association has led to a few trips to Johnson Space Center in Houston for behind-the-scenes tours, as well as opportunities to sample technology — including holding insulating tiles that are “almost weightless” — and view shuttle launches in person.
“It’s really pretty amazing. It never gets old,” she said.
Scott-Conner can separate the “cool factor” and the very serious work on committees. She was on a committee that issued the 2014 report titled, “Health standards for long duration and exploration spaceflight ethics principles, responsibilities, and decision framework.”
She said the objective of the cancer risk-assessment committee appealed to her after having served on a previous panel that identified toxic radiation exposure as one of the potential deal-breakers or insurmountable problems for a mission to Mars.
“You need to have people on these committees who have the general view and can look at it and say, ‘Yeah, it would be nice to build a rocket ship with better shielding. But anytime you design a new rocket, you take the risk for equipment failures,’” she said. “After all, what's killed most of the astronauts who have died in the space program? Things blowing up. So, you sort of need that generalist perspective. I think that's what I bring.”
The challenge, Scott-Conner said, is to conduct enough research to bring something new and different to the table. NASA has its own set of experts conducting research and checking off every angle. It’s on the National Academies’ committee members to present the best information and potential areas of research or aspects of a problem NASA hadn’t considered, Scott-Conner said.
“You have to approach it with a certain degree of humility and reverence,” she said. “You're just one part of the puzzle.”
‘All of medicine will benefit’
Those who work in the medical field know space exploration can yield important insights to improve patient care.
“There are some areas where you don’t know what the benefit will be until you do it,” Woloschak said. “For instance, the pacemaker came about because of the science that was used in space. All of medicine will benefit from going to Mars and doing medicine from that distance.”
Scott-Conner is interested in how the physiological adaptation to a different environment and the adaptation of microgravity could provide insight into fluid dynamics in the human body and potential future treatments.
Satcher is looking forward to seeing how a potential 3-year mission to Mars — and how astronauts survive it — could drive innovation.
“I think it would probably be good for that to be communicated better, that side of the reasons for space travel and space exploration,” Berrington de González said. “I think that maybe it gets lost on the general public. There’s a tendency to think it’s all about space tourism, even going to Mars. What’s not translated as well is that it can benefit medicine on Earth, and it has some more direct potential.”
Although they won’t be climbing into spacesuits to take part in those discoveries, the role leading experts in oncology play in ensuring the safety of space travel is gratifying and worthwhile.
“Working in a group, focusing on researching astronaut health and their risks in space,” Woloschak said, “it’s very special.”
For more information:
Amy Berrington de González, DPhil, can be reached at Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, 9609 Medical Center Drive, MSC 9778, Bethesda, MD 20892-9778; email: berringtona@mail.nih.gov.
Robert L. Satcher, MD, PhD, can be reached at Department of Orthopedic Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030; email: rlsatcher@mdanderson.org.
Carol Scott-Conner, MD, PhD, MBA, can be reached at Department of Surgery, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 375 Newton Road, Iowa City, IA 52242; email: carol-scott-conner@uiowa.edu.
Gayle E. Woloschak, PhD, can be reached at Department of Radiation Oncology, Feinberg School of Medicine, Northwestern University, 420 E. Superior St., Chicago, IL 60611; email: g-woloschak@northwestern.edu.
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