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CommunityHealthExercise: the ‘secret weapon’ against breast cancer

Exercising can reduce the chances of breast cancer returning by half, even if you don't start until after diagnosis, according to a new US study.
Anna PukasOctober 20, 202011 min
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breast cancer exercisePhoto by Logan Weaver/ Unsplash

Exercise improves your chances of surviving breast cancer and also lowers the chances of a recurrence by  as much as 50 percent.

Research over the years has gathered mounting evidence of a strong link between exercising and good outcomes for breast cancer patients. Now a new study, involving more than 1,300 women, shows that even gentle exercise, such as walking, greatly reduces both the chances of dying of breast cancer and of the cancer coming back after treatment.

“The magnitude of the benefits seen with increased activity was quite substantial,” says Dr Thomas Budd, of the Cleveland Clinic in Cleveland, Ohio, who was one of the authors of the study. “There was somewhere between a 40 to 50 percent chance of reducing the relative risk of the cancer coming back and even greater degrees in reduction in death.”

Even walking for just half an hour a day made a big difference.

“The patients who did the worst were those who had very little activity,” said Dr Budd.

What’s more, researchers found that patients who only started exercising after they were diagnosed were also less likely to die from breast cancer or suffer a recurrence.

“The patients who were inactive before treatment but who became active one year or two years later also had decreases in recurrence in breast cancer and death that were similar in size or magnitude with patients who had great degrees of activity,” said Dr Budd.

The benefits of exercise for cancer sufferers were already known, but researchers wanted to collect more evidence about how exercising might affect someone both before and after a breast cancer diagnosis. What was unusual about this study is that it collected information from patients with high risk cancer, where the illness was likely to spread or recur, and monitored their activity levels at several time points – shortly before diagnosis, during chemotherapy and after treatment was complete. Previous similar research on the subject has only collected data at one time point.

“Our data strongly suggest that the more consistently active patients were, the better they did,” said the study’s lead author, Dr Rikki Cannioto of Roswell Park Comprehensive Cancer Center in Buffalo, New York.

Women who did at least two-and-a-half hours of moderate exercise or 75 minutes of vigorous exercise a week (the minimum recommended by experts both in the US and the UK) both before diagnosis and after treatment had a 55 percent reduced chance of the cancer recurring and a 68 percent reduced chance of dying – from any cause, not just breast cancer.

Even if patients did not quite meet physical activity guidelines, “there was still a survival advantage,” said Dr Cannioto.

In women who did not do the recommended amount of exercise before diagnosis but were doing so by the time of their two-year follow-up, the chance of recurrence was reduced by 46 percent and the risk of dying fell by 43 percent.

The women in the study all underwent conventional cancer treatment and were monitored for 15 years or until they died. The study was conducted jointly by SWOG (formerly Southwest Oncology Group) Cancer Research Network, Cleveland Clinic, Roswell Park Cancer Institute and others and is published in the Journal of the National Cancer Institute.

Cancer specialists at the Mayor Clinic call exercise a “secret weapon” against breast cancer.

“Loving family members may be urging a person with a cancer diagnosis to rest, but that can lead to a functional decline,” says Sara Mansfield, a certified cancer exercise trainer at the clinic’s Healthy Living program.

Exercise raises the heart rate, making you feel warmer and breathe faster. Moderate exercise should leave you still able to talk but not sing. Examples of moderate intensity exercise include: brisk walking, cycling, dancing, hiking, rollerblading, playing doubles tennis, water aerobics and pushing a lawn mower.

Vigorous or intensive activity should leave you unable to say more than a few words without pausing for breath. Examples include running, fast swimming, cycling fast or uphill, aerobics, martial arts, skipping and playing sports such as football, hockey, rugby and netball.

Some studies have found that exercise during cancer treatment can actually trigger stronger anti-tumour activity in the immune system, slowing down the spread of cancer. A Danish study in 2017 found that adrenaline released during intensive exercise prevents the cancer from metastasizing (forming new tumours) elsewhere in the body. This not only restricts the spread of cancer but makes it easier to treat.

“Our study indicates that it’s probably optimal for women with breast cancer to perform high intensity exercise two to three times a week,” said Pernille Hojman of the Centre for Active Health at the Rigshospitalet in Copenhagen.

Exercise also helps with weight management; it is well-known that being overweight or obese is an important risk factor in cancer of the liver, pancreas, esophagus and endometrium (lining of the womb) as well as the breast. There is also increasing evidence that being overweight or obese can increase the risk of cancer recurrence and even death. Breast cancer is also linked to levels of estrogen, the female hormone, which is produced in the ovaries. After menopause, however, estrogen is produced mainly in fat tissue – another good reason to lose weight and reduce your body fat.

The British research charity Breast Cancer Now says there is no reason why people diagnosed with breast cancer should not remain as active as the general population, but recommends adding some muscle-strengthening exercise a couple of days week. If your treatment makes you feel too tired or unwell to exercise much, the charity suggests simply reducing the amount of time spent sitting down or being inactive, adding, “Any amount of activity is better than none.”

We should not get too carried way, however, with the idea that exercise is the magic bullet that kills breast cancer, warns Dr Joanne Elena, director of the genomics research program at the National Cancer Institute in the US.

“Physical activity is not the only factor that determines whether breast cancer will recur and it is certainly not the only determinant of death. It’s just one piece of the puzzle. We don’t want someone to think ‘If I exercise enough, I won’t have a recurrence.’”

But, she adds, the benefits are undeniable and the message for women who have or have had breast cancer, is clear.

“If you can add physical activity into your day, it is likely to influence many types of health outcomes for breast cancer survivors. Move as often as you can, whenever you can.”

Anna Pukas

Anna Pukas has reported from all over the world as a foreign correspondent for British media. She is now an editor based in Abu Dhabi.

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