The researchers examined genetic data, including blood samples, from a combined 275,000 women, 146,000 of whom had been diagnosed with breast cancer.
"The quebec program of breast cancer screening starts at 50 years old because it is considered that women begin to be at risk from that age".
Six months ago, something came up wrong in a mammogram for our own Stacy Lyn. "Women are very strong". As detailed earlier, most of the research has shown that people who increase their physical activity, improve their diet and stay at a healthy weight reduce their risk of chronic diseases and cancer.
Possessing a broken version of either of these genes is thought to account for as much as 10 percent of all breast cancers, and about 15 percent of ovarian cancers.
Dr Pallave Dasari, an Australian breast cancer research fellow at University of Adelaide, said that while she believed this was a "really valuable" progression in understanding family history risk, a test was "extremely premature" at this stage. A team at the Cleveland Clinic found differences in the types and amounts of bacteria between cancerous and non-cancerous breast tissue.
USA co-author Professor Peter Kraft, from the Harvard TH Chan School of Public Health, said the findings revealed a wealth of new information about the genetic mechanisms underlying the disease.
With what the medical community already knows about BRCA1, BRCA2, other variants, plus the newly identified genes, it's estimated that about 39 percent of heritable ER-positive breast cancer risk can be explained, researchers said. "This should provide guidance for a lot of future research".
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However, not all cancer cells carry this receptor - these are known as oestrogen-receptor negative.
Among breast cancer sufferers, those who rely on herbs, homeopathy or energy crystals to beat their disease are 5.68 times more at risk of an early death, a study found.
"We think that this ability to pinpoint the genes associated with risk of breast cancer will eventually enable us to develop more effective screening interventions and even risk-reduction medications and treatments", Dr Beesley said. "That is when it is curable and we have more treatment options if found early", McCain said.
Baroness Delyth Morgan, chief executive of the charity Breast Cancer Now, said: 'This is another exciting step forward in our understanding of the genetic causes of breast cancer.
A further seven genes were identified specifically in association with breast cancers that lacked oestrogen receptors, which don't tend to respond to hormone based therapies.