More than 1.3 million women worldwide are diagnosed with breast cancer each year, making it the second most common form of cancer behind lung cancer. Its prevalence, along with robust awareness-raising efforts (such as the pink-ribbon campaign), has given breast cancer a high public profile. Research into breast cancer's origins and pathology, as well as into treatment options, is therefore well funded.
As a result, the survival rates for breast cancer have improved markedly over the decades. In the 1960s, only 35% of women diagnosed with breast cancer in the United States would have been alive ten years later; by the mid-1990s, that figure was 77%. But nearly half-a-million women still die from this disease each year.
Not all breast cancer is the same, however. Women with certain types of breast cancer fare better than others (page S50), so understanding the different types is the next big challenge. One subgroup with a particularly poor prognosis is 'triple-negative' breast cancer. Here the tumour cells lack the three receptors commonly found in breast cancer, leaving drug developers with little to aim at. But researchers are uncovering new drivers and molecular targets for this subgroup that might provide a way in (S52).
Today the worst prognosis is for breast cancer that has already spread, or metastasized, to other sites at the time of diagnosis. What's more, tumour cells can hide quietly in distant organs before awakening and multiplying years or even decades after the initial treatment (S55). Preventing such metastases could save millions of lives, but real progress on this front will mean rethinking the way metastasis inhibitors are tested in clinical trials (S58).
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