Metastatic cancer is the kind of cancer that spreads from one part of the body to the other, in a process called “metastasis.” Met typically referred to as stage four cancer. This can be a devastating diagnosis to a patient. Researchers are finding hope on the horizon, though, with a promising new study showing how one particular lifestyle habit can actually help to slow down or even prevent cancer from spreading at all.
The study, published by Israeli researchers in the journal Cancer Research, points to a particular type of aerobic exercise which may reduce cancer’s propensity to spread.
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Aerobic exercise’s effect on metastatic cancer
Biochemists at the University of Tel Aviv evaluated data spanning 20 years from more than 2,700 Israeli men and women between the ages of 25 and 64 who were cancer-free at the start of the study. The participants filled out two physical activity questionnaires regarding vigorous and moderate activities that lasted at least 10 minutes.
The researchers also evaluated 14 male and female runners between ages 25 and 45, collecting data on their breathing, metabolic measurements, and blood samples, before and after the runners engaged in 30 minutes of exercise on the treadmill at the highest speed they could handle.
The researchers also evaluated groups of mice, one of them undergoing an eight-week exercise regiment—some of which were injected with melanoma cells to evaluate the relationship between spreading cancer and exercise.
According to the study, participants saw a “significantly reduced likelihood of highly metastatic cancer.” Further, the mice that received the cancer injection were “significantly protected against metastases in distant organs.” This could mean the exercise effectively protected the mice from cancer’s ability to spread from one organ to others.
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Cancer needs energy to spread
How exactly does this process work? It all comes down to the cells’ consumption of glucose, also known as sugar.
Because exercise increases glucose consumption (as the body consumes sugar for energy), there is less energy the tumor can use to help it grow or spread. “Cancer thrives on sugar and places an unusually high demand on it,” says Dr. Rand McClain, DO, a sports medicine physician based in Santa Monica, CA. He points out that because cancer cells often grow at a faster rate than normal human cells, they need more energy in order to spread. This, of course, happens at a slower rate if glucose is being used elsewhere—like to fuel a workout.
“[The study] finds that through exercise—particularly intense exercise—healthy cells are activated to require more glucose (and other necessary nutrients needed by both healthy and cancerous cells) and successfully compete for glucose at the expense of the cancer cells that do not receive their energy supply. The result is that cancer growth—particularly the cells that form metastases—is hindered or prevented substantially,” says Dr. McClain.
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The link between exercise and metastatic cancer
This isn’t the first time regular exercise has been linked to decreased cancer risk. Dr. McClain says, “[…In] terms of cancer risk, exercise engenders repair of DNA and up-regulates our antioxidant activity against free radicals, both of which protect against the mutations that can lead to cancer development. [Exercise] can also reduce excess inflammation and improve metabolic function, both of which can reduce the negative effects on healthspan.”
The recent study adds to growing research linking the use of muscle and decreased risk of spreading cancer.
“Exercise appears to prevent cancer development, growth, and metastasis by stimulating healthy ‘exercised’ cells to out-compete cancerous cells for energy and nutrients necessary for survival,” says Dr. McClain. “It is not a novel concept to understand that exercise prevents cancer, but elucidating the mechanism by which it occurs is a recent discovery.”
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What’s considered high-intensity?
While the study does specify high-intensity exercise, Dr. McClain points out that the research does not specify the type of exercise needed in order to reduce risk. While some runners were evaluated for the study, “high intensity” doesn’t just mean going for a run.
According to Dr. McClain, “high intensity” activity refers to any exercise that would be “close to one’s maximal effort,” bringing someone to a 90% or 100% maximal heart rate. However, any intense exercise requires cellular energy—even while doing household chores. So while high-intensity interval training tends to be a go-to, other activities like running, speed walking, biking, and hiking can all fit into this category.
“Any exercise would presumably be beneficial for not only improving overall health, but for activating healthy cells to compete for the energy (glucose) and nutrients to the detriment of cancer cells,” he says.
However, the study researchers did say there’s a lack of evidence about whether low-intensity exercise’ likewise affects glucose consumption. Further studies would need to take place in order to determine if every type of exercise would benefit, not just high intensity.
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Aim for 20 to 30 minutes a day
“Depending upon one’s age, health and current fitness, it is safe to say that as little as 20 to 30 minutes a day of any form of exercise–from gardening or walking to weight-lifting or sprinting–is beneficial,” says Dr. McClain.
And although some studies may suggest otherwise, Dr. McClain says that exercising at any time will help with reaping the benefits, with the exception of exercising too close to the bedtime. This doesn’t give the body enough time to let the core body temperature come down, and can delay sleep and affect sleep quality.
