News Release

Physical activity may improve survival and quality of life

Peer-Reviewed Publication

Norwegian Cancer Society

Physical activity may help cancer survivors cope with anxiety and side effects, improving immune function, metabolic hormones and weight control and thereby possibly improving survival.

Obesity and weight gain in breast cancer survivors are associated with significant distress, lymphoedema, and possibly an increased risk of recurrence and reduced survival. "Cancer patients who engage in a regular physical exercise programme display robust and clinically significant improvements in physical and mental health compared with patients who do not exercise", states Professor Kerry S. Courneya, a Canadian researcher from the University of Alberta. Courneya spoke to the 18th UICC International Cancer Congress in Oslo, Norway, this week.

Reduces fatigue
Many cancer survivors experience fatigue. Several studies, including one by Courneya and collaborators, found that rest was not the best way to 'treat' fatigue in cancer patients. Instead, they recommend daily exercise to reduce fatigue.

"How vigorously should patients with fatigue exercise?"

"They should avoid high intensity exercise. Brisk walking and bicycling is OK, but not jogging. I recommend 30 minutes a day five days a week. Fatigue is cyclical. Patients should be advised to exercise on days with low fatigue and at a time of the day when they feel OK", responds Courneya.

Prevents weight gain
Breast cancer survivors often gain weight after chemotherapy, commonly 2.5 to 6.2 kilograms. This weight gain occurs without any gain in lean body mass. The cause of the weight gain is unknown but recent research suggests it may be due more to physical inactivity than to overeating or a reduction in resting energy expenditure.

Interventions that increase physical activity, may result in an appropriate energy balance in breast cancer survivors, thereby enhancing quality of life.

Six studies on breast cancer patients and a study on patients that have received bone marrow transplants give some proof that physical activity prevents weight gain after diagnosis. Two studies from Edmonton, Canada, show that the patients did not change weight, but that skin fold thickness was reduced, indicating a loss of fat.

Survival
As for the survival rate, very few studies have been made, but extrapolations of data from other studies support the hypothesis that breast cancer patients may survive longer if they are physically active.

"At least weight gain and obesity are linked to relapse. Obesity seems to be a problem for everything. As for hormones, obesity is linked to levels of oestrogen, insulin and insuline-like growth factor (IGF), as well as immune function and all sorts of problems", says Courneya.

"In a study on breast cancer survivors, we found improvements in a number of immune system components as a result of exercise, for example, an increase in natural killer (NK-cells) cytotoxic activity. We also found changes in insulin-like growth factor, he says.

Courneya believes several factors may be involved in extending the survival rate for breast cancer patients who are physically active. Immunological and several humoral factors may play a role. Sex steroid and metabolic hormones may also be involved, as well as hormonal changes caused by reduced weight.

Courneya advises cancer patients not to gain weight at all unless they are underweight to begin with: "There seems to be a linear relationship between health and weight gain. But one should not weigh too little either, a BMI of 20 – 24 is ideal. The greatest risk is for obese patients with a BMI above 30." He also recommends physical activity for overweight patients who cannot achieve weight loss. "Physical activity is an independent factor, reducing risk independently of weight," he says.

Research in the field of rehabilitation and lifestyle tends to lag behind studies on primary prevention. "In the next 5 to 10 years, we will see more results from studies on quality of life and exercise, as well as survival and exercise", predicts Courneya.

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