Scientists previously thought that hormone dependent breast cancers, which usually require treatment with surgery and anti-hormone drugs, originated from the same biological pathway as hormone independent breast cancers, which are treated with surgery and chemotherapy.
In the largest study of its kind, an international consortium of cancer researchers studied the genetic makeup of over 23,000 breast cancer cases.*
Dr. Paul Pharoah, lead author based at the University of Cambridge, said: "We looked at five genetic variants associated with breast cancer to see if they were more likely to be found in hormone dependent or independent breast cancers. One common genetic variant, FGFR2, was strongly associated with hormone dependent breast cancer, but weakly associated with hormone independent cancer. This shows that they have distinct genetic origins, and are different diseases."
Dr Lesley Walker, Cancer Research UK's director of cancer information, said: "Scientists were previously unsure how different types of breast cancer developed. Although the findings won't have any immediate effects on the treatment of women with the disease, they are important in helping to define the next steps in our research on the causes of this major cancer."
This discovery provides strong evidence that the subtypes originate from separate pathways and could guide future research into prevention and treatments for the cancer types as different diseases. This study was funded by Cancer Research UK.
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"The majority nevertheless had estrogen-sensitive and more readily treated tumors. And women who develop breast cancer at a higher age often do better than those who get it earlier in life," says Helena Jernstr?śm.
She stresses, however, that it is too early to make any dietary recommendations regarding coffee consumption.
"This is new information that needs to be corroborated in other studies before we can issue any recommendations. If coffee does in fact provide some protection against breast cancer, then women in such a coffee-drinking country as Sweden ought to have fewer cases of cancer than other countries. This is also the case, at least compared with the U.S. There the proportion of breast cancer cases in the population is considerably higher, and there people drink both more decaffeinated coffee and less coffee in general."
These research findings are published in the journal Cancer Epidemiology, Biomarkers and Prevention, with doctoral student Erika B??geman as lead author.
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