Simple Exercise Habits May Improve Cancer Outcomes

We know exercise is good for us. It improves mood, helps us achieve restful sleep, and allows our immune system to operate on high alert — ready to battle threats. And the best part is it’s free and as easy as stepping out the door for a brisk walk.

Now, a new study reveals that regular weekly exercise, of moderate intensity activity the year before a cancer diagnosis can slow cancer progression and improve survival. Even less than 60 minutes weekly of any moderate intensity exercise — enough to get your heart rate up and quicken your breathing — improved the odds of decreasing cancer’s progression and improved mortality. That’s less time than most people spend scrolling through social media each day.

Making small changes in habits, like hitting the gym a couple of times a week or going for brisk walks, won’t just boost today’s energy but may improve your future self’s ability to survive cancer.

Plenty of people could use the benefit

Cancer continues to have a tremendous global impact. In 2022, there were an estimated 1.9 million new cancer cases diagnosed in the US, and 608,366 people died of cancer — more than 1,600 deaths every day.

Unfortunately, the incidence of cancer isn’t slowing. In the coming year, according to The American Cancer Society, new US cancer cases are expected to cross the two-million mark, a depressing milestone. That’s nearly 5,500 people a day receiving a life-altering diagnosis.

Given the uptick in cancer incidence, the decline in the cancer death rate in the past 30 years in the US is threatened. If more people are diagnosed with cancer, then more people will likely die from it. That’s why any intervention that could slow the progression of this crippling disease is critical, and it might be as simple as getting up and moving.

“Physical activity may confer substantial benefits in terms of progression and overall mortality to those diagnosed with cancer,” the study’s authors from Canada and South Africa conclude.

The scientist’s findings align with a growing body of exercise research, especially exercise oncology, that has exploded in the last decade and provided evidence that exercise, at least after a cancer diagnosis, is associated with longer survival. The association is strongest for breast and prostate cancer and has prompted The National Cancer Institute to recommend that cancer survivors follow public health guidelines for regular exercise, which suggest 2.5 to 5 hours of moderate physical activity or 1.25 to 2.5 hours of vigorous activity weekly.

However, not much research has focused on whether exercise prevents the progression of cancer and whether exercise before a cancer diagnosis offers protection.

Small amounts of exercise, big future cancer benefits

The study tracked participants enrolled in a South African health plan’s vitality program, which collected their physical activity through fitness devices, logged gym attendance, or involvement in organized fitness activity which was translated into weekly minutes of moderate intensity exercise.

The study spanned 15 years, during which 28,000 of the participants were diagnosed with stage I cancer — an early stage where cancer hasn’t spread. The scientists analyzed each person’s physical activity for the 12 months prior to diagnosis. Participants were then followed for the length of time to disease progression, death, or exit from the study.

The researchers stopped tracking exercise after a cancer diagnosis to avoid bias, since many cancer patients decrease their activity levels due to feeling unwell.

The participants were divided into three groups:

• No physical activity: People who didn’t record any exercise activity in the year prior to their diagnosis.
• Low amount of physical activity: Less than 60 minutes of moderate intensity exercise per week.
• Moderate to high amount of activity: 60 minutes or more of moderate intensity exercise per week.

Cancer progressed in just over a third of the cases, and 19% died before the end of the study. The average time to progression was seven months, and the average time to death was 20 months. But those who exercised before their diagnosis had significantly better outcomes and the greater the number of minutes spent exercising, the greater the impact:

Reduction in cancer progression

Low activity minutes: 16% reduction in cancer progression risk compared to no activity.

Moderate to high activity minutes: 27% reduction in cancer progression risk compared to no activity.

Reduction in mortality

Low activity minutes: 33% reduction in mortality risk compared to no activity.

Moderate to high activity minutes: 47% reduction in mortality risk compared to no activity.

“Knowing that as little as 60 minutes of regular weekly exercise may reduce the likelihood of cancer progression by 27% and death by 47%, should encourage all doctors to use exercise as medicine,” Jon Patricios, MD, Professor of Sports and Exercise Medicine, Wits University, South Africa, and lead author, said in a statement.

However, since the study was ultimately an observational study, it cannot prove cause and effect. Though the researchers tried to account for many sociodemographic factors like BMI and confounding diseases, they couldn’t control for all variables, for instance, the entire cohort is South African.

While the likelihood of disease progression and mortality increased as time went on, it was still lower for those who had clocked up some level of physical activity in the year preceding their diagnosis.

The study also found that exercise before a cancer diagnosis had a greater impact on how long people lived than how fast their cancer progressed.

For example, two years after diagnosis, 95% of those who were physically active were still alive, compared to 91% of those who were inactive. This pattern persisted at the three and five-year mark. In comparison, two years after diagnosis, 78% of those who were physically active had no cancer progression compared to 74% of those with no physical activity had no progression.

Exercise as cancer therapy

Scientists believe several biological mechanisms may explain why and how exercise is linked to slowing cancer and improving survival. Chief among them are:

Immune System Boost

Exercise increases the number and activity of immune cells, like macrophages, natural killer cells, neutrophils, and T cells, studies show. These cells identify and destroy cancer cells. In fact, natural killer cells increase 30 minutes after exercise and stay elevated for three to four hours.

Anti-Inflammatory Effects

Chronic inflammation fuels the development and progression of cancer. Exercise has been shown to increase anti-inflammatory cytokines (like IL-10) while reducing pro-inflammatory cytokines (like IL-6 and TNF-α), effectively shutting down cancer-causing inflammation.

Hormonal Regulation

Physical activity can lower circulating estrogen, progesterone, or testosterone levels, which benefits some types of cancers that are hormone-sensitive, like breast, uterine, and prostate cancer. Exercise also reduces insulin levels, another hormone that promotes tumor growth.

The study had several strengths, such as a large number of participants, the 15 years of follow-up, and the non-reliance on the use of questionnaires for exercise data. But further reproducible studies are needed. Future research might explore how exercise after diagnosis affects outcomes and if any pre-exercise benefits extend to those diagnosed with stage II or III cancer.

The good news is that it’s never too late to get active. Whether you’re hitting the gym, taking a brisk walk, or shoveling snow, these activities might help protect you in the future.

The authors say it best: “Regular physical activity is the most powerful and accessible prescription we can give our patients.”