Is it mainly down to luck, genes or lifestyle - and can you avoid getting it? Find out with our quiz.. By Madeleine Bailey
Breast cancer affects more than 45,000 women (and 300 men) a year in the UK and while eight out of 10 now survive, the disease has increased by 50% in 25 years.
But while it has a pretty high profile, there's a lot of misunderstanding, too.
So how much do you really know about the risks and how they affect you? Take our quiz and find out...
(1) What's the biggest risk factor for breast cancer in women? a) Family history b) Age c) Smoking
Answer: b) Age We hear about breast cancer running in families but only 5% of cases are actually caused by genes. However, if you do have certain genetic faults - the BRCA1 and BRCA2 genes - your risk of getting the disease could be as high as 55-85%.
By far the biggest risk factor is age. The longer we live, the more chance there is that cells will malfunction, causing cancer. For instance, an average 29-year-old woman has a one in 2,300 chance of developing breast cancer but by the time she reaches 84, that's increased to one in 10. The younger a person is when they develop breast cancer, the more likely it is that genes are involved.
Studies have not so far found a connection with smoking.
(2) Does being overweight increase risk? a) Yes b) No, it lowers it c) It depends on your age
Answer: c) It depends on your age Confusingly, being overweight before the menopause seems to lower risk but afterwards it increases it.
Prolonged exposure to the hormone oestrogen can stimulate breast cancer cells to grow, and overweight women tend to ovulate less often, reducing their exposure.
But after the menopause, oestrogen levels are actually boosted by fat so the more fat you have, the bigger your risk. That's why older obese women are nearly a third more likely to have breast cancer than slim ones.
(3) Which of these definitely increase risk? a) Alcohol b) Late menopause c) Starting periods early d) The Pill e) HRT (hormone replacement therapy) f) Deodorants g) Underwired bras h) Stress
Answer: a) b) c) d) e) Even moderate drinking is bad news, with just one unit a day (half a small glass of wine, a half-pint of lager or a single pub measure of spirits) upping risk by about 10%. Of course, if your risk is small to begin with, the increase will be small, too.
Research last year among one million women suggested that 5,000 cases a year in the UK could be booze-related.
A late menopause can make breast cancer more likely as does starting your periods early, probably because it increases your breast cells' exposure to oestrogen.
The Pill slightly raises risk, but this drops back to normal 10 years after you've stopped taking it.
