More Genetic Insights Into 3 Types of Cancer03/27/13
WEDNESDAY, March 27 (HealthDay News) -- Critical clues to
understanding who is at the greatest risk for particular types of
cancer may be found in "spelling mistakes" contained in a person's
In a step toward personalized medicine and the ability to better
understand individual risk factors for three common hormone-related
cancers, a large team of international researchers have unveiled
what might be the clearest picture to date of the genetic
alterations associated with some forms of the disease.
Although more research is needed, the study authors predict that
genetic testing to help determine a person's risk for some of the
most potentially deadly cancers may be available within five to 10
"We think the most immediately practical application will be in people already at risk for the disease and going through the genetic counseling process," said Douglas Easton, a professor of genetic epidemiology at the University of Cambridge, in England.
A combination of five studies that include work from 160
different research groups has identified more than 80 genetic
errors that are linked to increased risk of breast, prostate and
ovarian cancers. The research was published March 27 in the journal
More than 2.5 million people worldwide are diagnosed with these
three types of cancers each year, according to the researchers.
Everyone has some of the so-called spelling mistakes, often
called "snips" (single nucleotide polymorphisms, or SNPs), the
researchers said. Problems are signaled by errors in the sequence
of genetic elements (bases), where letters representing the
elements -- A, G, C and T -- are incorrectly placed.
The sequence of bases in a portion of a DNA molecule, called a
gene, carries the instructions that are needed to create a protein.
Although some errors affect small things, others may be responsible
for increasing vulnerability to certain forms of cancer. The impact
on a person depends on where on the strand of DNA the genetic
alteration is located.
The studies from the European-based consortium -- collectively
known as the Collaborative Oncological Gene-Environment Study, or
COGS -- compared 100,000 patients with breast, ovarian or prostate
cancer to 100,000 healthy people.
The massive collaboration involved more than 130 institutions
for the breast cancer study, more than 100 institutions for the
ovarian cancer study and 70 for the prostate cancer study.
Researchers did genetic analyses of all the participants,
studying 200,000 particular sections of the DNA strand. Certain
variations were associated with increased risk of disease. For
example, researchers found the following:
- Breast cancer: 49 spelling mistakes (SNPs), more than double
what had previously been discovered
- Prostate cancer: 26 new deviations, which adds up to a total of
78 SNPs now linked to the disease
- Ovarian cancer: Eight new SNPs associated with this form of
What's more, the scientists identified DNA regions that suggest
a shared genetic basis and mechanism among all three cancers.
"There were clearly a number of regions where you get SNPs for more
than one cancer," Easton said. "There are a number of other regions
where we presume there are particular genes important for a range
of cancer types."
Implications of the enormous research effort are far ranging,
the scientists said. As the precise role of genetics in cancer is
better understood, lifestyle factors will continue to be seen as
critical, even in cancers that are considered closely tied to
genetics, said Dr. Paul Pharoah, a senior clinical research fellow
at the University of Cambridge.
"It's quite clear from what [we] understand about the genetics of these cancers that the lifestyle or environment act in concert with the genetics," Pharoah said. "So whatever your level of genetic risk, it's influenced by lifestyle. It's clearly wrong to think of the genetic component as in any way deterministic."
Understanding how this research will play out in terms of
screening, prevention and treatment will require more research,
ideally by an international effort similar in scale to the COGS
studies, the authors wrote.
A commentary published with the studies, written by Pharoah and
others, explored the possibilities of how this sort of genetic
analysis could make prevention and treatment programs more
"First, appropriate systems for inviting and recalling people for risk assessment and screening need to be in place," the authors wrote. "Second, there should be a standard protocol for taking consent, performing genetic sampling and using a standardized risk-assessment tool to integrate genetic data from an individual with environmental, lifestyle and hormonal data."
Ultimately, a person's level of risk of cancer will dictate what
care and treatments will be offered, they concluded.
Learn more about cancer and genetics from the
U.S. National Cancer Institute.
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