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New
test may mean faster breast cancer treatment
(HealthDay News) -- A new genetic test that analyzes
a set of 50 genes to identify four types of breast cancer
could lead to quicker, more immediate treatment for
patients, according to U.S. researchers who developed
the test.
“Unlike a widely used genomic test that applies
only to lymph-node-negative, estrogen-receptor-positive
breast cancer, this new genomic test is broadly applicable
for all women diagnosed with breast cancer,” Dr.
Matthew Ellis, of the Siteman Cancer Centre at Washington
University in St. Louis and Barnes-Jewish Hospital and
a breast cancer specialist, said in a university news
release.
Ellis and his colleagues analyzed the gene activity
of more than 1,000 breast tumors and identified 50 genes
that could be used to identify each of the four types
of breast tumors -- luminal A, luminal B, HER2-enriched
and basal-like. A genetic test called OncotypeDx, which
is currently in wide use, doesn’t identify all
four tumour types, according to background information
in the news release.
“Our test is the first to incorporate a molecular
profile for the basal-like type breast cancers,”
Ellis said. “That’s important because these
breast cancers are arguably the most aggressive yet
the most sensitive to chemotherapy. By identifying them,
we can ensure they are treated adequately.”
The new test also identifies what’s often considered
a fifth breast cancer type, known as normal-like. But
the researchers discovered that, instead of being a
fifth type of breast cancer, normal-like is an indicator
that a breast tumor sample contains insufficient tumor
cells to make a molecular diagnosis and that a new sample
needs to be taken.
The researchers also said that the 50-gene test was
highly accurate in predicting how 133 breast cancer
patients would respond to chemotherapy. Luminal A was
not sensitive to chemotherapy, which suggests that women
with this good-prognosis type of breast cancer can forgo
chemotherapy in favor of hormone-based therapy, they
said. Among poor-prognosis types of breast cancer, they
found that basal-like was the most sensitive to chemotherapy
and luminal B the least sensitive.
The study was published online Feb. 9 in the Journal
of Clinical Oncology.
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