New Genetic Clues to Breast Cancer?01/23/12
SUNDAY, Jan. 22 (HealthDay News) -- Researchers have identified
three new genomic regions they believe are linked with breast
cancer that may help explain why some women develop the
All three newly identified areas "contain interesting genes that
open up new avenues for biological and clinical research," said
researcher Douglas Easton, a professor of genetic epidemiology at
the University of Cambridge in England.
Breast cancer is the most common cancer among women, with about
1 million new cases annually worldwide and more than 400,000 deaths
Scientists conducting genome-wide association studies --
research that looks at the association between genetic factors and
disease to pinpoint possible causes -- had already identified 22
breast cancer susceptibility loci. Locus is the physical location
of a gene or DNA sequence on a chromosome.
"The three [newly identified] loci take the number of common susceptibility loci from 22 to 25," said Easton.
However, the three new susceptibility loci might explain only
about 0.7 percent of the familial risks of breast cancer, bringing
the total contribution to about 9 percent, the researchers
Michael Melner, scientific program director for the American
Cancer Society, said this current research adds some important new
clues to existing evidence, but he agreed that the number of cases
likely associated with these three variants is probably low.
"So the total impact in terms of patients would be fairly small," Melner said.
The study is published online Jan. 22 in
To find the new clues, Easton's team worked with genetic
information on about 57,000 breast cancer patients and 58,000
healthy women obtained from two genome-wide association
The investigators zeroed in on 72 different single nucleotide
polymorphisms (SNPs). A SNP -- pronounced "snip" -- is a change in
which a single base in the DNA differs from the usual base. The
human genome has millions of SNPs, some linked with disease, while
others are normal variations.
The researchers focused on three SNPs -- on chromosomes 12p11,
12q24 and 21q21.
Easton's team found that the variant on the 12p11 chromosome is
linked with both estrogen receptor-positive breast cancer (which
needs estrogen to grow) and estrogen receptor-negative breast
cancer. The other two variants are only linked with ER-positive
cancers, they said.
One of the newly identified variants is in an area with a gene
that has a role in the development of mammary glands and bones.
Easton said it was already known that mammary gland development in
puberty is an important period in terms of determining later cancer
risk. "But these are the first susceptibility genes to be shown to
be involved in this process," he said.
One of the other SNPs is in an area that can affect estrogen
receptor signaling, the researchers found.
Melner, noting some of the research is "fine tuning" of other
work, said in his view the new understanding of the signaling
pathways and their genetic links is the most important finding.
"When you delineate a pathway, you bring up new potential targets for therapy," he said. "The more targets you have, you open up the potential for having multiple drugs and attacking a cancer more easily, without it becoming more resistant."
Overall, Melner added, the results underscore the complexity of
the different mechanisms involved in breast cancer development.
For more about the genetics of breast cancer, visit the
American Cancer Society.
Copyright © 2012
. All rights reserved.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.