Oncotype
DX™ Expands its Role in Guiding Optimal Treatment Decisions
in Women with Early Breast Cancer
According to results recently presented at the 40th annual
meeting of the American Society of Clinical Oncology (ASCO),
the laboratory test called Oncotype DX™, which has already
been approved for determining the risk of a recurrence in
breast cancer, may also help detect which patients with breast
cancer will respond to chemotherapy. Results from Oncotype
DX™ may help guide patients to the most effective individualized
treatment options for their cancer.
Breast cancer is responsible for approximately 40,000 deaths
annually in the United States alone. However, if breast cancer
is detected early, prior to the spread of cancer, cure rates
remain high. Although patients with early breast cancer derive
a significant survival benefit overall with the addition of
chemotherapy in their treatment regimen, some women may be
exposed unnecessarily to chemotherapy, suffering from side
effects caused by the treatment while gaining no benefit.
By using a test such as Oncotype DX™ to determine whether
a patient is likely to achieve benefit from chemotherapy and/or
is likely to experience a cancer recurrence, physicians can
tailor treatment to meet the needs of individual patients.
This also allows patients who are not likely to benefit from
specific chemotherapy agents to seek other treatment options.
Oncotype DX™ is a test that uses breast cancer biopsies,
or small tissue samples, to determine whether a patient has
breast cancer. The test analyzes the expression of specific
genes or clusters of genes of the cancer cells and, through
statistical analysis, can provide associations between the
expression of one or more genes and specific outcomes of patients,
such as risk of a cancer recurrence. Oncotype DX™ is
presently approved to determine the risk of a distant recurrence
in women with node-negative, estrogen receptor-positive breast
cancer through the evaluation of 21 genes.
Researchers from Italy recently conducted a study to further
evaluate Oncotype DX™ and its ability to predict an
anti-cancer response to chemotherapy in women with early breast
cancer. Previous studies have indicated that a complete disappearance
of cancer following treatment upon evaluation under a microscope
of a tissue sample, referred to as a pathologic complete response,
has been demonstrated to improve cancer-free and overall survival
in previous clinical studies. The study included 89 patients
who had their biopsy specimens analyzed by Oncotype DX™
prior to any treatment. The patients were initially treated
with a taxane (Taxotere ® or paclitaxel), followed by the
surgical removal of their cancer, followed by further chemotherapy
with a regimen referred to as CMF (cyclophosphamide, methotrexate,
5-fluorouracil), radiation therapy and tamoxifen (Nolvadex ®)
if they were estrogen receptor-positive. Twelve percent of
patients achieved a pathologic complete response. The results
from Oncotype DX™ identified the expression of 86 genes
that were associated with the achievement of a pathologic
complete response. Expression of these genes tended to be
from 3 gene groups: an estrogen receptor group, an immune
group and a proliferation group. Patients with a higher expression
of genes in the estrogen receptor group had a significantly
lower rate of a pathologic complete response, while patients
with a high expression of genes from the immune group and
proliferation group had a higher rate of a pathologic complete
response. Furthermore, when compared to the genes that predict
for the risk of a distant recurrence, patients at a higher
risk for a recurrence also have significantly higher rates
of a pathologic complete response following treatment.
The researchers concluded that Oncotype DX™ helps predict
a pathologic complete response following chemotherapy for
patients with early breast cancer. The fact that patients
who are identified to be at a high risk for developing a distant
recurrence also tend to achieve pathologic complete responses
following therapy led to greater evidence that these patients
will achieve improved survival with additional treatment.
Further studies will help elucidate exactly which patients
will benefit from specified therapeutic approaches, leading
the field of oncology into individualized treatment for patients.
Reference: Gianni L, Zambetti M, Clark K, et al. Gene expression
profiles of paraffin-embedded core biopsy tissue predict response
to chemotherapy in patients with locally advanced breast cancer.
Proceedings from the 40th annual meeting of the American Society
of Clinical Oncology. 2004. Abstract #501.
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