Study unpicks gene changes behind breast cancer

Scientists have mapped the complete genetic codes of 21 breast cancers and created a catalogue of the mutations that accumulate in breast cells, raising hopes that the disease may be able to be spotted earlier and treated more effectively in future.

The research, the first of its kind, untangles the genetic history of how cancer evolves, allowing scientists to identify mutational patterns that fuel the growth of breast tumors, and start to work out the processes behind them.

"These findings have implications for our understanding of how breast cancers develop over the decades before diagnosis in adults and might help to find possible targets for improved diagnosis or therapeutic intervention in the future," said Mike Stratton, who led the research team.

Breast cancer kills more than 450,000 women a year worldwide and is the most common cancer among women, accounting for 16 percent of all cases, according to the World Health Organization (WHO).

A study last year by the Institute for Health Metrics and Evaluation in the United States found that global breast cancer cases have more than doubled in just three decades, from 641,000 cases in 1980 to 1.6 million cases in 2010 - a pace that far exceeds global population growth.

U.S. Breast Cancer Statistics - About 1 in 8 U.S. women (just under 12%) will develop invasive breast cancer over the course of her lifetime.

- In 2011, an estimated 230,480 new cases of invasive breast cancer were expected to be diagnosed in women in the U.S., along with 57,650 new cases of non-invasive (in situ) breast cancer.

- About 2,140 new cases of invasive breast cancer were expected to be diagnosed in men in 2011. A man's lifetime risk of breast cancer is about 1 in 1,000.

- From 1999 to 2005, breast cancer incidence rates in the U.S. decreased by about 2% per year. The decrease was seen only in women aged 50 and older. One theory is that this decrease was partially due to the reduced use of hormone replacement therapy (HRT) by women after the results of a large study called the Women's Health Initiative were published in 2002. These results suggested a connection between HRT and increased breast cancer risk.

- About 39,520 women in the U.S. were expected to die in 2011 from breast cancer, though death rates have been decreasing since 1990 - especially in women under 50. These decreases are thought to be the result of treatment advances, earlier detection through screening, and increased awareness.

- For women in the U.S., breast cancer death rates are higher than those for any other cancer, besides lung cancer.

"This is the first time we've been able to delve fully into breast cancer genomes in such a thorough way," said Peter Campbell, head of cancer genetics and genomics at the Wellcome Trust Sanger Institute in Cambridge, where the studies were led.