What do astronauts and cancer patients have in common? Well, maybe more than one would think, at least when it comes to physical activity.

According to a new commentary published online in the journal Cell, fitness programs geared to astronauts before taking off into space may be applicable to patients with cancer.

Both groups experience similar multisystem physiologic toxicities that are driven by comparable pre-flight risk factors, as in the case of astronauts, or pre-diagnosis risk factors for patients with cancer. The direct and indirect consequences of spaceflight or anticancer treatment are also comparable, say the authors, led by Jessica Scott, PhD, an exercise physiology researcher at Memorial Sloan Kettering Cancer Center in New York City.

The team notes that during the past 6 decades, since the advent of the space program, NASA has developed a sophisticated countermeasures program (CMP) to both characterize and diminish the physiologic consequences of spaceflight. They emphasize that cancer is the only major chronic disease condition in which a comparable CMP is not part of standard care.

This is surprising, they say, since there are "remarkable similarities" between astronauts and cancer patients. These similarities are seen in both pre-flight and pre-diagnosis risk factors, direct acute harmful exposure, as well as effects caused by the spaceflight itself or cancer therapies that result in multisystem adverse events.

In their new study, the authors propose a model based on the NASA CMP that can potentially help diminish or even prevent some of the physiologic toxicities associated with both cancer and its treatment.

Multiple Hits

"Both spaceflight and cancer therapies impact almost every system in the body," said Scott. "For example, astronauts and cancer patients may have decreases in bone, muscle, and heart size, and astronauts experience something called 'space fog,' which is similar to what cancer patients call 'chemo brain.' "

These changes are caused by what is known as "multiple hits," explained Scott, who also worked at the NASA Johnson Space Center when doing her postdoctoral fellowship.

The first hit involves baseline risk factors. Both patients with cancer and astronauts may have a preexisting risk factor such as hypertension. "Back in the 1960s, several astronauts smoked," she told Medscape Medical News.

The second is a direct hit, such as chemotherapy in cancer and the absence of gravity for astronauts. The third is an indirect hit, in that patients may feel sick during therapy, which can reduce their activity levels.  "For astronauts, there is no standing up in space, so spaceflight is like lying in bed for months," said Scott. "When you put these multiple hits together, both astronauts and cancer patients may experience side effects from the head to the toes."

Prepare for the Mission

One difference between astronauts and patients with cancer is that a space mission is not an unexpected event. In that sense, they begin preparing far in advance for travel into space and are aware of the health issues that may occur as a result of space travel. In contrast, cancer is something that catches people unprepared and they haven't been "training" in advance to deal with it.

But Scott doesn't see that as an issue and explained that oncologists are like rocket scientists in that they prescribe the appropriate "fuel" to target malignant cells. "At NASA, aerospace engineers also aren't asked to design an exercise program — individuals called the Astronaut Strength, Conditioning and Rehabilitation specialists (ASCRs) provide exercise programs," she said. "There is constant communication between groups at NASA, such as how much oxygen is consumed during an exercise session and how that may impact the International Space Station Environmental Control and Life Support System. Each group is responsible for a puzzle piece to ensure mission success."

A similar team approach is likely needed in oncology, in which clinicians will ask patients about their current levels of physical activity and then refer them to exercise programs. Importantly, for both astronauts and patients with cancer, "one size of exercise does not fit all."

"The goal of a countermeasures program is to identify patients that may benefit from a structured exercise program, and then deliver a more targeted approach to exercise, just like patients receive different types, doses, and schedules of therapy," Scott said.

Mission Control in Manhattan

In their study, Scott and her colleagues point out that translating the NASA program to the clinical care setting will require rigorous evidence showing that a cancer-specific CMP is a cost-effective strategy that confers a benefit across clinical outcomes.

At MSKCC, elements of the NASA countermeasures program are already being implemented in some of their clinical trials. "For example, we are using certain assessments that are identical to those used in astronauts," she said. "We also started delivering treadmills to patients' homes and conducting supervised exercise sessions from our 'mission control' at Memorial Sloan Kettering in Manhattan with video conferencing, just as astronauts hundreds of miles above Earth have exercise prescriptions delivered."

Using this method, patients don't have to travel three to five times per week to complete their supervised exercise sessions, which in turn substantially decreases the burden for patients currently receiving therapy.

Exercise Still Lagging

An ever-growing body of evidence points to the benefits of exercise in cancer care, and some professional groups are taking notice. The Clinical Oncology Society of Australia (COSA), the country's leading organization for cancer professionals, issued a position statement that exercise should now be a part of the standard of care in treating all patients with cancer. Last month, a global coalition of 40 leaders from 17 organizations, spearheaded by the American College of Sports Medicine, also stated that exercise prescriptions should now be standard of care for all appropriate oncology patients and physical activity "should become a vital sign, similar to blood pressure," recorded at each patient visit.

But even with the expanded literature on exercise and cancer outcomes and professional groups stepping up to the plate, it is still not standard of care. Scott, however, believes that her team's work will make a difference. The researchers are exploring the impact of exercise from a rather unique standpoint.

"Compared to exercise in heart and lung diseases, exercise-oncology is a very young field," she said. "Evidence to date in cancer patients indicates that increasing exercise by even just an hour per week is better than being sedentary."

But there is much research and many clinical trials that need be completed assessing the safety, feasibility, and efficacy of a countermeasures program before incorporating this approach into a standard of care for cancer patients, Scott added.

Coauthor Lee Jones is supported by research grants from the National Cancer Institute; Jones and Scott are supported by AKTIV Against Cancer and the KavliTrust; Scott, Jones and coauthor Larry Norton are supported by the Memorial Sloan Kettering Cancer Center Support Grant/Core Grant.

Scott has disclosed no relevant financial relationships. Jones has stock ownership in Pacylex, Inc and coauthor Lianne Dolan will be working for AstraZeneca Canada.

Cell. Published online November 14, 2019. Full text

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