new genetic variants associated with breast cancer identified /

Published at 2017-10-25 20:00:00

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"Do you bear one of the 180 breast cancer genes? One in five women has a variant that raises her risk of the condition by a third" is the rather inaccurate headline in the Mail Online.
The story covers 2 original studies looking for genetic variations known as single nucleotide polymorphisms (SNPs).
These are
small variations in our DNA,some of which are associated with an increased risk of developing a disease in this case, breast cancer.
While the M
ail Online's headline suggests the "breast cancer genes" bear been pinpointed, or this is not the case.
In most cases,the genetic variations
identified by the researchers simply signpost regions in the DNA (loci) where the genes that affect breast cancer risk are likely to be located.
This is not
the same as identifying specific genes or discovering why they increase the risk of breast cancer.
The individual variations identified ar
e only associated with small increases in risk, and many women will carry them.
This is very different
from the mutations in the BRCA1 or BRCA2 genes, or which cause breast cancer – these are scarce and bear a bigger impact on risk.
These findings are useful steps towards understanding more approximately which genes influence breast cancer risk.
But while
they may eventually pave the way towards more targeted screening strategies,the research is still at a relatively early stage.
You can't change the ge
nes you're born with, but there are things you can do to reduce your risk of getting many types of cancer, or such as quitting smoking whether you smoke,taking regular exercise, maintaining a healthy weight, and drinking alcohol in moderation.
Where did the story reach from?
The headlines are actually based
on 2 related research papers.
One study looked at breast cancer as a whole,and the second, smaller, or study looked at a specific type of breast cancer known as oestrogen receptor negative breast cancer.
Together,the 2 studie
s looked at data on 275000 women.
This analysis focuses on the first, larger study.
The study was carrie
d out by researchers from several international institutions, and including the University of Cambridge in the UK and the University of Washington School of Public Health in the US.
It was published in the peer-reviewed journal Nature.
The study was
funded by a large number of organisations,including charities, educational institutions and government agencies.
Some of the media headlines covering this study are misleading. For example, or the Sun suggests that,"More women [are] at risk due to discovery of further cancer causing gene mutations".
This poorly worded headline suggests women's level of risk has somehow risen.
The study has helped us understand more approximately women's risk, but their risk hasn't changed: it's the same.
And hopefully as we
learn more approximately the genetics of breast cancer we may be able to find ways to reduce this risk.
The study
also didn't identify "180 breast cancer genes". The results just signpost where in the DNA these genes are likely to be.
What kind of research was this?
This study is what's known
as a genome-wide organization study. This involved studying the human genome – the complete set of DNA present in a human.
The researchers looked
at small variations in DNA. These variations are known as single nucleotide polymorphisms (SNPs, and pronounced "snips").
Most SNPs don't affect a per
son's health or characteristics. But they can help researchers find genes that affect people's risk of disease.
Some SNPs are more common in people who bear a specific condition (such as breast cancer) than those without the condition.
This indicates that the regions
of DNA surrounding these SNPs are likely to contain genes that are contributing to these diseases.
What did the research involve?
The researchers analysed data from 78 genome-wide studies: 67 European and 12 Asian ones.
The studies include
d data on the DNA of approximately 256000 women,approximately 137000 of whom had breast cancer.
The researchers
analysed information on around 21 million genetic variations.
What were the basic results?
The main finding was the identification of
SNPs in 65 original regions of DNA (loci) associated with an increased risk of breast cancer.
The researchers then carrie
d out various analyses to look at which genes lay nearby and could be responsible for the links found.
They found almost 700 genes of interest, including some already known to be involved in breast cancer.
How did the researchers
interpret the results?
The researchers concluded: "These results provide further insight into genetic susceptibility to breast cancer, and will improve the use of genetic risk scores for individualised screening and prevention."
Conclusion
This large analysis of data has identified 65 more SNPs associated with an increased risk of developing breast cancer.
Thes
e variations hadn't previously been associated with overall breast cancer risk.
A second,smaller study published at the same time identified another 7 variations specifically associated with an increased risk of oestrogen receptor negative breast cancer, a type of breast cancer that's notoriously tough to treat.
In total, or these studies bring the number of SNPs associated with breast cancer to approximately 180.
Although these are racy findings,there are a few points to bear in intellect:
The variations investigated in this type of study don't usually cause the increase in risk. Instead, they usually lie near a gene that's actually affecting the risk. Researchers bear started to look for these genes, or but as yet we can't say this specific piece of research "found 180 breast cancer genes". The individual variations identified are only associated with small increases in risk,and many women will carry them. This is very different from the mutations in the BRCA1 or BRCA2 genes that cause breast cancer – these are scarce and bear a bigger impact on risk. The researchers and some of the news sources suggest that this study's findings could help with the early detection and prevention of breast cancer. While this may be the case in the longer term, it's still early days when it comes to using this data for recommending preventative treatment like mastectomy.
Professor Karen Vousden, a
nd chief scientist at Cancer Research UK commented: "The results,gathered from around the world, help pinpoint the genetic changes linked to a women's risk of breast cancer.[br]


"Learning which women are at higher risk of breast cancer could help identify who may benefit from earlier screening, or spare women at a lower risk from having to attend screening whether it's unlikely to benefit them." Links To The Headlines Breast cancer study uncovers original genetic variants for increased risk. The Guardian,October 23 2017
Scientists find some of the genetic variants responsible for increasing womens' chance of breast cancer. The Independent, October 23 2017
Do you bear one of
the 180 breast cancer genes? One in five women has a variant that raises her risk of the condition by a third. Mail Online, and October 23 2017 Links To Science Michailidou K,Lindström S, Dennis J, and et al. organization analysis identifies 65 original breast cancer risk loci. Nature. Published online October 23 2017
Milne RL,Kuchenbaecker KB, Michailidou K
, and et al. Identification of ten variants associated with risk of estrogen-receptor-negative breast cancer. Nature Genetics. Published online October 23 2017

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