Why cancer patients should exercise

• Keeping fit both protects bodies from disease, reduces perceived memory problems, boosts chances of survival
• Working out in pregnancy ‘good for mom, baby’

Large studies have shown how athletes suffer markedly fewer cancers of the lungs, kidneys, breasts, ovaries and cervix.

Investigators have in the past suggested that there may be a simple explanation: athletes eat more healthily and are less likely to smoke.

But now there is evidence showing that in fact it is exercise itself that protects our bodies against cancer in complex ways.

Furthermore, for patients who have cancer, exercise may significantly boost their chances of survival. Nor do you have to be a champion athlete to reap these benefits.

Danish researchers in a study published in journal Cell Metabolism said that adrenaline, which gets released when we exercise, is a key to the protective effect.

The Copenhagen University Hospital doctors injected cancer cells into two groups of mice. The first had activity wheels on which they could run as much as they liked. The second group had no exercise other than moving inside their cages.

Dr. Pernille Hojman, the oncologist who led the study, says that when the mice were exposed to a chemical known to cause liver cancer, only a third of the exercise group developed tumours compared with three- quarters of the non-exercisers.

Furthermore, the tumours that did grow in running-wheel mice were around 60 per cent smaller than those in their sedentary counterparts.

When Hojman studied the tumours in the exercising mice, she found that they contained more infection-combating cells than the sedentary animals’ cancers.

From this, she discovered that a type of immune defence cell called a natural killer cell was fighting cancers in the exercising mice.

Adrenaline is known to power our natural killer cells. And another exercise-induced chemical, interleukin-6, helps these immune cells to target tumours.

When Hojman’s team injected adrenaline and interleukin-6 into cancerous sedentary mice, the rodents’ immune systems attacked the tumours as effectively as if they had been exercising regularly.

Writing in the journal Cell Metabolism, Hojman said that the combined hormone therapy could help people who are too old or too ill to be active to get some cancer- fighting benefits of physical exertion.

However, she is quick to downplay the idea that ‘exercise in an injection’ could help those who are merely lazy, as exercise carries other important anti-cancer benefits.

Crucial among these is the power of exercise to reduce inflammation, the body’s mechanism for fighting infections. But as we age, our defences become increasingly prone to producing excess inflammatory chemicals.

Meanwhile, engaging in moderate-to-vigorous physical activity appears to indirectly reduce perceived memory problems in breast cancer survivors – likely by increasing self-confidence and reducing fatigue and distress.

The study found breast cancer survivors who engaged in higher levels of moderate-to-vigorous physical activity appeared to experience reductions in perceived memory impairment.

These were the findings of a new study led by Northwestern University in Chicago, IL, United States (U.S.), and published in the journal Psycho-Oncology.

A surprising suggestion from the results was that memory problems appear to be linked to high stress in breast cancer survivors, rather than specifically as a result of chemotherapy or radiation treatment.

Lead author Siobhan Phillips, assistant professor of preventive medicine at Northwestern University Feinberg School of Medicine, said: “We found moderate to vigorous physical activity actually benefits women psychologically and that, in turn, helps their memory.”

The study involved 1,477 female breast cancer survivors recruited after their treatment had finished. The women completed surveys about their physical activity, self-efficacy, distress, fatigue, and perceived memory impairment. They completed the surveys twice: once at the start of the study and then again 6 months later.

Self-efficacy is a definition of self-confidence that psychologists use – defined as believing in one’s ability to achieve goals and chosen levels of performance.

To assess distress, the surveys asked questions relating to depression, concerns about cancer recurrence, perceived stress, and anxiety.

A randomly selected subgroup of 362 participants also wore accelerometers, devices that measure amount of physical activity.

The researchers found higher levels of moderate-to-vigorous physical activity were linked to reduction in perceived memory impairment – both in the overall group (based on self-reports) and in the subgroup (based on accelerometer readings).

In addition, the researchers found more physical activity was linked to higher levels of self-efficacy, and lower levels of distress and fatigue.

They say the findings support their theory that physical activity indirectly influences perceived memory impairment via exercise self-efficacy, distress and fatigue.

Moderate-to-vigorous activity includes exercise that challenges you enough to make you breathless and sweaty – for example brisk walking, cycling, jogging, and taking part in exercise classes.

Deaths from breast cancer have been falling since about 1989. The biggest drop has been in women under 50, likely due to earlier detection, increased awareness, and better treatments.

Meanwhile, a new study that reviews and analyzes the evidence, confirms what many studies have found – exercise during pregnancy is safe and can benefit both mother and baby.
The researchers say their analysis reinforces the view that exercise is good for a pregnant woman and her baby and does not hold any increased risk of preterm birth.

The study is published in the American Journal of Obstetrics & Gynecology.

Senior author Vincenzo Berghella, professor at Thomas Jefferson University in Philadelphia, PA, and director of its Division of Maternal-Fetal Medicine, says: “The thinking was that exercise releases norepinephrine in the body, which is a chemical that can stimulate contractions of the uterus, and thus lead to preterm birth.”

He and his colleagues pooled and analyzed data from nine randomized controlled studies.

Overall, the analysis included 2,059 women: with about half assigned to an aerobic exercise group and half assigned to a control group.

The women in the exercise group did aerobic exercise for 35-90 minutes, three or four times a week for 10 weeks – or up until their delivery. The controls did no exercise.

The results showed there was no significant difference between the exercise and control groups in terms of incidence of preterm delivery (before 37 completed weeks of gestation).

However, there was a higher incidence of vaginal delivery (73.6 percent versus 67.5 percent), and a significantly lower incidence of cesarean delivery (17.9 percent versus 22 percent) in the exercise group than in the control group.

Also, the researchers found a lower incidence of gestational diabetes and lower incidence of high blood pressure in the exercise group compared with the control group.

Looking at the babies, the researchers found no differences in low birthweight and average birthweight between the exercise group and the control group.

All the pregnant women in the analysis were carrying a single baby – no twins – and they were of normal weight to start with. There were also no health problems that prevented them from exercising.

Prof. Berghella says the results support the current guidelines from the American Congress of Obstetricians and Gynecologists (ACOG), which follows the Centers for Disease Control and Prevention (CDC) recommendation that pregnant women get at least 150 minutes of moderate-intensity aerobic activity every week.

However, he also acknowledges that “there are many reasons women pull back on exercise during pregnancy – discomfort, an increase in tiredness and feeling winded by low level exertion.”

Aerobic exercise is activity that moves the large muscles of the body – such as those of the legs and arms – in a rhythmic way (for example as in swimming and walking).

Moderate intensity means the exercise raises heart rate and the body starts to sweat – “you can talk but you can’t sing” is a useful way to think of it.

Examples of moderate-intensity aerobic activity include swimming, brisk walking, and general gardening (such as raking, weeding, or digging).

However, the ACOG guidelines also recommend that even if they are healthy, pregnant women check with their doctor or healthcare team member during early prenatal visits and get their advice on what kinds of exercise are safe and fit their needs.

A person can achieve 150 minutes a week by doing 30-minute aerobic workouts on five days of the week. It is just as effective to do 10-minute bursts of equivalent intensity activity two or three times every day.

Numerous studies have demonstrated how chronic inflammation can damage the Deoxy ribonucleic Acid (DNA)/genetic material inside our cells, making them significantly more likely to turn cancerous.

Chronic inflammation has also been found to raise the risk of some tumours, such as breast cancer, recurring.

Australian researchers reported in the journal Breast Cancer Research & Treatment earlier this year that gentle weight-training can significantly lower inflammation levels in women who don’t normally exercise.

They studied 39 women who had survived breast cancer and found that when the women exercised three times a week, the levels of inflammatory chemicals in their bodies dropped significantly — which should reduce the risk of the disease recurring.

Exercise also appears to stimulate the release of another tumour-fighting substance — the brain chemical dopamine, say Chinese scientists.

They found that when mice with liver cancer were made to swim regularly in moderate amounts, levels of dopamine increased in their bodies. The tumours in these mice shrank.

The researchers reported in the journal Oncogene that when they gave the mice a drug that blocked the action of dopamine, the cancer- fighting benefits of moderate exercise disappeared.