May 10, 2011

AUSTRALIA: Busting breast cancer myths

SYDNEY, NSW / The Sydney Morning Herald / Life & Style / Wellbeing / May 10, 2011

Chew On This

Paula Goodyer
is a Walkley award winning
health writer

Myth ... lifestyle factors, not stress, heighten breast cancer risk.

When Melbourne researchers asked a group of breast cancer survivors recently if they thought anything could have contributed to their developing the disease, more than half nominated stress. It was an echo of a 2003 survey by the then National Breast Cancer Centre that found many women believed a blow to the breast could increase the risk of cancer. Both studies found there was less awareness of what really could raise the risk of breast cancer – not stress, not a thump on the breast – but lifestyle factors like being overweight.

“One problem is that people tend to see overweight and lack of physical activity as risk factors for heart disease, not cancer,” says Professor Robin Bell, co-author of the study and Deputy Director of the Women’s Health Program at Monash University’s Alfred Hospital. “We know there are risk factors for breast cancer like family history and age that we can’t do anything about. I’d like women to concentrate on things they can do to reduce the risk like maintaining a healthy weight.”

Why should extra kilos boost a woman’s breast cancer risk? Probably the effect of extra oestrogen. Too much of this hormone - which accumulates in fat – can target breast tissue and promote tumours, explains Kellie Bilinski, Senior Clinician Dietitian with the Westmead Breast Cancer Institute.

“Being overweight can also increase levels of insulin circulating in the body, and insulin is another hormone which can encourage tumours to grow. Extra weight increases a woman’s risk of breast cancer after menopause rather than at a younger age, but there’s some evidence that younger women who do develop breast cancer do worse if they’re overweight.”

The good news is that being physically active reduces breast cancer risk both before and after menopause, partly because it helps to keep the kilos off but also because it reduces levels of oestrogen, according to the National Breast and Ovarian Cancer Centre. It’s not clear yet what the best exercise ‘dose’ is to get a benefit but a number of studies suggest four or more hours weekly of moderate to vigorous exercise is protective and that the more active women are, the lower their risk.

But why are we less aware of all this and so ready to believe the myths instead?

“I don’t know if it’s a lack of awareness or not wanting to know,‘ says Bilinski who wonders if some women want a simple reason to blame breast cancer on or if making changes like losing weight or getting more exercise can seem too hard.

“I get the feeling some women would like me to say ‘eat a pomegranate’ rather than recommend weight loss, but the reality is we don’t know much about dietary factors and breast cancer. The best advice we can give is to eat a healthy balanced diet that also helps to keep the weight off,” she says. “With meat, for example, there’s no strong evidence linking it to breast cancer – the World Cancer Research Fund recommends no more than 500g of meat a week (similar to current Australian guidelines) but that mainly relates to bowel cancer risk. There’s no strong evidence for fat in the diet either. If you do a search on the internet you’ll come up with studies showing a link with meat and fat but the evidence isn’t strong. Some research suggests a high fibre diet may be protective but again it’s not well established, although it may help indirectly by helping to keep weight down.”

Eating plenty of folate, a B vitamin found in spinach and broccoli, for example, may reduce the risk of breast cancer associated with alcohol according to the NBCCC.

“With alcohol and breast cancer the research is consistent that more than one drink a day increases breast cancer risk. It’s a small risk and we’re not trying to stop women from drinking – but we want them to be aware,” Bilinski says.

Can getting enough vitamin D be protective against breast cancer? That’s another question that researchers, including Bilinski, are trying to answer.

“In animal studies adequate vitamin d helps cells divide normally, and some human studies suggest that people have less breast cancer and other cancers when they have high levels of vitamin D – but the evidence is inconsistent.”

Is it news to you that being overweight can increase breast cancer risk?

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