New
Test for Detecting Risk of Recurrence in Women with Node-Negative
ER-positive Breast Cancer now Available
Genomic Health recently announced that its test that details
the genetic make-up of breast cancer, Oncotype DXTM, is now
available for clinical use in most states. Oncotype DXTM is
a clinically validated assay that evaluates a tumor’s
expression of 21 genes and quantifies the likelihood of a
distant recurrence in women with node negative, ER positive
breast cancer.
The optimal strategy for treatment of women with localized
breast cancer who do not have axillary lymph node spread has
not been identified and continues to be a topic of research.
However, it is clear that without adjuvant therapy a significant
number of women with node-negative breast cancer will relapse.
For patients who are hormone receptor positive, anti-estrogen
therapy is usually administered. For women who are hormone
receptor negative, chemotherapy is usually given. Age or menopausal
status may determine the type of adjuvant therapy administered.
Identifying the molecular basis of each node-negative cancer
may provide an even more precise way to individualize treatment.
Oncotype DXTM may be a valuable tool for identifying gene
expression in breast cancer.
Oncotype DXTM measures expression of 21 genes and generates
a Recurrence ScoreTM , which indicates the risk that an individual’s
cancer will recur. The gene panel contains 16 breast cancer-related
genes and 5 reference genes. Oncotype DX™ utilizes formalin-fixed,
paraffin-embedded tumor tissue, which is an advantage over
other molecular diagnostic methods because this form is usually
readily available because it is routinely generated following
tissue biopsy and is easily stored.
Oncotype DXTM was prospectively validated by the National
Surgical Adjuvant Breast and Bowel Project (NSABP) that involved
668 women with node negative, ER-positive breast cancer treated
with tamoxifen. The Recurrence ScoreTM is calculated from
the tumor's expression of 21 genes which include those measuring
proliferation, HER-2, estrogen, and invasion. The scale of
the score is 1-100. Patients with a score of <18 have a
low risk of recurrence, those with a score of 18-31 have an
intermediate risk, and those with a score of 31 or more have
a high risk of relapse.
Data from the NSABP trial (see table 1) demonstrated that
the Recurrence Score™ is a strong predictor of distant
recurrence-free survival, relapse-free survival, and overall
survival (see table 1).
Table 1 Oncotype DX clinical validation data with distant
recurrence and survival as endpoints
Risk group % of patients 10 year distant recurrence 10 year
survival
Low (score <18) 51% 6.8% 90%
Intermediate (score 18-31) 22% 14.3% 78%
High (score >31) 27% 30.5% 68%
Recurrence ScoreTM was a better predictor or recurrence than
standard measures such as patient age, tumor size, and tumor
grade. 2
References
1. Tefferi A, Wieben ED, Dewald GW, et al. Primer on Medical
Genomics Part II: Background Principles and Methods in Molecular
Genetics. Mayo Clinic Proceedings 2002;77:785-808.
2. Paik S, Shak S, Tang G, et al. Multi-gene PT-PCR assay
for predicting recurrence in node negative breast cancer patients—NSABP
studies B-20 and B-14. Proc of the 26th Annual San Antonio
Breast Cancer Symposium. December 3-8k, 2003; San Antonio,
TX, Abstract #16.
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