The number of women with breast cancer is rising, with one in eight now developing the disease, figures show.
Breast cancer rates in the UK have increased by 3.5% over the last decade, with 47,700 women diagnosed in 2008 compared with 42,400 in 1999. This has pushed up the lifetime risk of the disease from one in nine women to one in eight.
Experts have blamed lifestyle factors, including obesity and drinking alcohol, for fuelling the rise.
Women are also more likely to have children later in life, and fewer offspring, which influences the risk. Having a family history of the disease also increases a woman's chance of developing the disease, which kills about 12,000 in the UK every year.
The latest data, from charity Cancer Research UK, is published on World Cancer Day.
It reveals the biggest rise in breast cancer rates has been among women aged 50 to 69. Over the decade, cases rose by more than 6% in this age group while rates among younger women (25 to 49) dropped slightly by 0.5%.
In 2008, around 22,900 women aged 50 to 69 were diagnosed with breast cancer - 48% of the total number of cases. Some 15,700 cases (33%) were in women over 70 and 9,100 cases (19%) in those aged 25 to 49.
However, more women are surviving the disease, with almost two-thirds living more than 20 years beyond diagnosis. More than three-quarters of women diagnosed with breast cancer survive for at least 10 years.
Women in England aged 50 and over are eligible for breast cancer screening every three years. By 2012, this will be extended to women aged 47 to 73. Around 1.5 million women are screened in the UK every year.
Sara Hiom, Cancer Research UK's director of health information, said: "Mammograms will pick up breast cancers early on before they can be felt as a lump or spotted through other visible changes. We know that the earlier a cancer is detected the more successful treatment is likely to be so women can benefit by taking up invitations to breast screening."