Is fitness advice for people with cancer changing?

Fifteen years ago, when I started caring for patients with cancer, we were mostly worried about cachexia—involuntary weight loss. Recommendations included getting plenty of rest and even eating ice cream! Cachexia is still a big problem for many cancers, including breast, but we now know that weight gain, especially increased body fat and loss of muscle, are bigger problems.

Is exercise a good idea if you have a breast cancer diagnosis?

It’s important before, during and after treatment. Physical activity prevents deconditioning and weight gain, and women feel better; they have less anxiety and depression. It’s also important for cardiovascular health.

What about its effect on breast cancer itself?

In animal studies, when we put rats and mice on an exercise program, tumors grow more slowly. We know less about direct effects on breast cancer in humans. In one small human study we’ve done in women assigned to an exercise program, there was a direct genetic effect on tumor tissue. Something changed within the cancer that could be related to the cancer’s aggressiveness.

Does this translate to better outcomes or less recurrence?

In population studies, people who exercise more are less likely to develop breast and other cancers, and women who exercise after a breast cancer diagnosis are less likely to have a recurrence. But we don’t know exercise is actually responsible. So we are studying a combined diet and exercise program in women who are obese or overweight when they are diagnosed with breast cancer to see if helping them change these factors will affect the risk of the cancer coming back, and of dying from breast cancer.

How are you studying this?

3,136 women will be randomized to usual breast cancer care or to a two-year telephone coaching program for weight loss and fitness. They’ll aim for 150 minutes of mostly aerobic activity a week and then try to push that to 200 during the weight maintenance phase. They’ll get Fitbit activity trackers and wireless scales to monitor weight. We expect results in 2024.

What fitness recommendations do you have now? 

Current guidelines now recommend that all patients diagnosed with cancer try to become more physically active. The goal is 150 minutes of aerobic activity plus two strength training sessions a week. But even a lower level of activity will mean less weight gain, feeling better and less fatigue. The best treatment for fatigue is actually exercise.

How should people start if they haven’t been particularly active?

Start really slow, perhaps 10 minutes three times a week. Try to walk around the block. When you can do that without shortness of breath, do it twice. Even if you were really active before, don’t try to go back to that level right away. It can help to work with a trainer—ask your care team. 

Have you seen exercise benefit women with breast cancer?

Many say how becoming physically active helps them get back to feeling really good. So many pieces of cancer are out of their control, but this is something they can do for themselves.