HEALTHWATCH
LOSING EXTRA KILOS CAN HELP TO LOWER YOUR CHANCES OF GETTING BREAST CANCER
Reduce your cancer risk
There are some risk factors associated with breast cancer that you can’t do anything about, like family history. But there are others that you may be able to change. Go for it. Fighting fit!
Donna Fleming HEALTH EDITOR
Scientists don’t really understand what causes breast cancer, but they have been able to pinpoint some of the factors that increase our risk of getting it.
As much as we don’t want to hear this, we have to face up to the fact that being overweight or obese is one of the things that makes us more likely to develop the disease, which is diagnosed in around 3300 Kiwi women every year.
Many studies have shown that there’s a link between carrying excess weight – and in particular surplus body fat – and breast cancer caused by hormones.
Being overweight is particularly risky if you’ve been through menopause. It also increases the chances of the cancer returning if you’ve already been diagnosed with the disease.
So losing weight is a no-brainer, but as everyone knows, that is easier said than done. Still, there’s some good news: exercise may be able to help reduce your risk. Not only may it help you to lose some of those extra kilos, but it seems it works in other ways to help lower your chances of getting breast cancer, or of it coming back again after treatment.
Here’s what we know now about weight, exercise and breast cancer.
HAVING EXCESS BODY FAT INCREASES YOUR RISK OF BREAST CANCER
We know about the association between body fat and breast cancer thanks to many studies that have been carried out over the years. They’ve revealed that fat cells don’t just sit there taking up space – they are biologically active and produce the hormone oestrogen. Too much oestrogen can trigger the development and growth of breast cancer cells.
The type of cancer caused by too much oestrogen is known as hormone receptor-positive cancer, or ER-positive. Around 80% of breast cancers are ER-positive.
Research also shows that extra fat cells can trigger long-term, low-grade inflammation in the body, which causes the immune system to release proteins that seem to encourage breast cancer cells to grow, especially in postmenopausal women.
People who are overweight
also tend to have higher levels of insulin, and there is a link between this hormone and a number of cancers, including breast cancer.
So those fat cells – which are also implicated in other health conditions like diabetes, heart attack and stroke – are doing you no favours. In fact, they can be potentially very dangerous. YOU CAN APPEAR TO BE A HEALTHY WEIGHT, BUT HAVE EXCESS FAT CELLS What’s also concerning is that even women who have a normal BMI and seem to be a healthy weight could have an increased risk if they have excess fat cells. Fat that builds up around the organs in your abdomen – known as visceral fat – may not change your shape much, but it can still be there pumping out extra oestrogen.
One of the researchers from a US study carried out last year says they hope the findings will alert women to the fact that they may have an increased breast cancer risk, even if they are a healthy weight, if they have visceral fat in their abdomen.
The study found that women with a healthy BMI but high body fat (which they measured with a special scan called a DXA that looks at body composition) had almost twice the risk of developing ER-positive breast cancer than those who were within the healthy BMI range and had low body fat.
THE SIZE OF YOUR WAIST IS IMPORTANT
Carrying extra weight around your middle – even if other parts of your body are slender – can be a red flag. Extra fat around the waist raises the risk of breast cancer more than that deposited on your hips and thighs. It’s thought this is because that abdominal fat
pumps out more hormones. Unlike subcutaneous fat, which sits under your skin, visceral fat is hard to see. High-tech scans such as MRI and DXA are the only way to accurately measure how much you have. But as a guideline, having a waist measurement of over 80cm is an indication that you may have a build-up of fat in your abdomen.
LOSING WEIGHT CAN HELP Don’t think, “Oh, it’s too late, I’ve been overweight for years – I have done the damage”. So far, studies show that overweight postmenopausal women who manage to lose even just 5% of their body weight can reduce their chances of getting breast cancer. A study of data collected by the Women’s Health Initiative in the US – which has tracked the health of more than 160,000 postmenopausal women for up to 25 years – found that women who lost 5% or more of their body weight were 12% less likely to be diagnosed with breast cancer. And when they lost 15% or more of their body weight, the risk dropped to 37% less likely.
The results were encouraging, say the researchers, because the women involved didn’t necessarily have to lose enough weight to get into the healthy range established by BMI to reduce their breast cancer risk. That means every kilo you lose helps.
EXERCISE IS VITAL – AND NOT JUST TO HELP YOU LOSE WEIGHT
If you need to shed kilos, exercising can help, although experts say you shouldn’t depend solely on physical activity to help you get rid of weight – you should also change your diet. ( There’s a school of thought that successful weight loss is best achieved with 80% dietary changes and 20% exercise.) But it’s not just its ability to help you slim down that makes exercise so crucial when it comes to trying to avoid breast cancer, or to the disease coming back after treatment.
It’s not fully understood why, but it appears exercise seems to reduce the risk of cancer developing because of its effect on hormones and also the body’s immune system.
There’s lots of different advice about how much exercise you need to do to try to keep breast cancer at bay. But generally, it’s thought doing at least 150
minutes a week of exercise that makes you breathe harder is a good thing to aim for.
According to some research, doing twice that amount (so five hours of exercise per week) can help to reduce the risk of cancer returning if you have already had it. Always check with your specialist if you have had cancer and are planning on starting to exercise.
Exercise can have other benefits for breast cancer patients. If they are able to do regular physical activity they may notice that they have less severe side effects from treatment such as chemotherapy. MUSCLE MASS MATTERS Unless you’re a regular gymgoer or sports person, you probably don’t give too much thought to your muscle mass. But having strong muscles is extremely important for good general health, and can make a difference when it comes to breast cancer.
Research published earlier this year showed that low muscle mass – or sarcopenia, to give it its medical name
– may affect survival rates when it comes to breast cancer. The study of more than 3000 women found that women with low muscle mass were about 40% more likely to die from breast cancer or another health issue.
The Californian researchers found women who had both low muscle mass and high levels of fat cells in their bodies had the worst survival rates.
“The study highlights the benefits of keeping yourself active and maintaining muscle mass before, during and after breast cancer treatment,” says lead researcher Bette Caan. So it is important to do musclebuilding exercises as well as aerobic ones.
That doesn’t mean you have to join a gym, although regular workouts there can definitely help to improve your muscle mass. Physical activity done at home, such as gardening, can also help to strengthen muscles, as can simple exercises using dumbbells or exercise bands.