by Liz Szabo, USA TODAY
Scientists announced Sunday that they have finished mapping
virtually all of the genetic mutations in breast cancer, an effort that
could soon change the way patients are treated and eventually help
researchers develop better treatments.
"The catalogue of human
breast cancers is nearly complete," says study co-leader Matthew Ellis
of the Washington University School of Medicine in St. Louis. "It's the
breast-cancer equivalent of putting a man or woman on the moon."
Among
the most striking findings: One of the most lethal types of breast
cancer is genetically closer to a kind of ovarian cancer than it is to
other breast tumors, according to the paper, published online today in Nature.
That
discovery could soon produce real benefits for breast cancer patients,
Ellis says. Women with so-called basal-like breast tumors -- also known
as triple-negative cancers -- would likely do better on a much less
toxic chemotherapy regimen, which is currently the standard of care in
ovarian cancer.
Such shifts show that doctors are beginning to
change the way they look at cancers, focusing less on a tumor's organ of
origin and more on the inner workings of its nucleus, down to the
molecular level, Ellis says.
"Just because it's a breast cancer
doesn't mean it's like every other breast cancer," says Brad Ozenberger,
who oversees the research project, called The Cancer Genome Atlas, at
the National Institutes of Health.
The ambitious federally funded
program -- with a budget of $100 million a year -- aims to be the cancer
equivalent of the Human Genome Project, which decoded and mapped the
human genetic blueprint. Scientists already have published the genomes
of four other cancers: brain, ovarian, colorectal and lung. In this
study, scientists analyzed tissue from 348 breast cancers, finding that
most tumors are caused by mutations in 30 to 50 genes, Ellis says.
The
genome atlas could give drug companies ideas for new drugs that target
key genetic mutations in cancer, Ozenberger says. In addition, the
catalogue of genetic mistakes can also help scientists better understand
how cancers develop and spread, Ozenberger says.
For example,
they may discover that a newly discovered gene is involved in the immune
system -- providing a clue to how cancer eludes the body's normal
defenses. Already, the program has given researchers clues that both
ovarian and triple-negative breast tumors could be vulnerable to drugs
that block new blood vessel growth, which aim to starve tumors.
Triple-negative
tumors account for about 10% to 15% of all breast cancers, and are more
common among younger women and African Americans. Today, women with
triple-negative tumors are treated like many other breast cancer
patients, getting drugs called anthracyclines that can damage the heart
and cause leukemia or a type of "pre-leukemia," called myelodysplastic
syndrome, or MDS. Ellis' recent research, however, suggests
anthracyclines don't help women with triple-negative tumors.
Robin Roberts, host of Good Morning America,
underwent a bone-marrow transplant Thursday for MDS, caused by her
successful treatment for triple-negative breast cancer in 2007. Another
insight from the study: Doctors should reconsider an experimental class
of drug called PARP inhibitors for triple-negative breast cancer,
because early trials in ovarian cancer have been promising, Ellis says.
Breast
cancer survivor Roxanne Martinez says she "choked up" when she heard
that future patients might be able to skip the most toxic
chemotherapies. Martinez, 32, was treated for triple-negative disease
two years ago, while she was pregnant with her daughter.
While
both she and her daughter are currently healthy, Martinez says
anthracycline drugs made her very sick. Now, she worries about her
long-term health. Martinez, of Forth Worth, says she's fascinated by the
similarities between breast and ovarian cancers, which run in her
family. Doctors have long known of links between breast and ovarian
tumors.
One of the best known breast cancer genes, BRCA1,
dramatically increases the risk both of ovarian cancer and
triple-negative breast tumors. Martinez says she's thrilled that women
with triple-negative tumors -- who today have the fewest treatment
options -- could have better care due to this study. "Just the idea of a
targeted treatment plan, that gives me so much hope," Martinez says.
Copyright 2012 USA TODAY