Exercise and Cancer Risk

Being physically active is one of the few changeable things with consistent evidence behind it for breast cancer, although its benefits are often oversold. In this video, I'll explain what the evidence shows, how much activity helps and how to stay active safely during and after treatment. In large studies, the most active women have around a 13 percent lower risk of breast cancer than the least active. That's a comparison between groups of women, not a promise about any one woman's risk. People who exercise also tend to smoke and drink less, which makes the effect harder to separate. Activity seems to help in several different ways at the same time. It reduces body fat, which after the menopause becomes the main source of oestrogen. It also lowers inflammation and improves how the body handles insulin, a hormone that can encourage cells to divide. That's important because each time a cell divides, there’s a small chance of an error that could lead to cancer. Body weight affects breast cancer risk differently on either side of the menopause. Before, extra weight is linked with a slightly lower risk, but afterwards, it raises this risk. That later effect is the larger one. So, this is no reason to gain weight, because the weight we carry into midlife is what drives that risk later on. The UK guideline is 150 minutes of moderate activity a week, such as brisk walking, with, muscle strengthening on two days. Any increase in exercise counts; and you should treat the 150 minutes as a goal to work towards, rather than a pass mark you have to reach. The strength part is the one most people skip, and only around one woman in twenty-five in England manages it. Yet it matters a great deal, because it helps protect your bones and keeps your muscles strong through treatment. It can also ease the joint pain that some hormone treatments cause. If you're starting from nothing, build up gradually over a month. Begin with a ten-minute daily walk, at a pace where you could talk but not sing. In week two make it two walks a day, and in week three add two short strength sessions at home. By the fourth week, aim to make your walks longer rather than faster. After a breast cancer diagnosis, being active is linked with lower death rates, but it hasn't been shown to stop the cancer coming back. So if it does return, it isn't a verdict on how you lived. The evidence is firmest for quality of life, with less fatigue and better mood during and after treatment. The strongest evidence on exercise after cancer treatment comes from a large trial in bowel cancer. People on a structured exercise programme were more likely to be alive and free of cancer five years later, although a few more had aching joints. No trial like this has yet been done in breast cancer, so we can't promise the same. The old advice to protect your arm after breast surgery came from a worry that using it would overload the remaining lymph drainage, but it has largely been overturned. Instead, build strength work back gradually; ideally with supervision at first, rather than going straight back into heavy lifting. If you're having treatment or had surgery recently, start from the exercises your own team gave you, which usually begin the day after surgery. Full shoulder movement is needed to plan radiotherapy; so ask for a physiotherapy referral if your shoulder is still stiff weeks later. Stop and get help if your arm on the treated side becomes red, hot and painful, because that needs assessing the same day. New swelling; chest pain; unusual breathlessness; or bone pain that wakes you at night also need prompt attention from your team. For further information, our booklet goes into greater detail regarding the evidence and the safety advice related to exercise. If you'd like to talk about what's right for you, please get in touch with me or my team.