Genomic Health Update, Breast Cancer Advocate News

Genomic Health is pleased to announce that ER (Estrogen Receptor) and PR (Progesterone Receptor) Scores, based on the assessment of the expression of each of these genes, has been added to all Oncotype DX reports as of February 1, 2008. These scores are now being included on a standard second page of the report (see below), with the Recurrence Score result reported on the first page.

Recent data reported at the ASCO Breast Symposium in 2007 showed a high correlation between ER and PR status (positive or negative) as determined by the Oncotype DX test (using RT-PCR technology) versus traditional immunohistochemistry (IHC). Determining ER and PR expression by RT-PCR provides a quantitative result (numeric value), which is reported to physicians along with an interpretation of how that measure relates to the ER and PR positive or negative status as reported by other testing methods. An ER Score value of 6.5 is the cut-off between ER negative and ER positive values. A PR Score value of 5.5 is the cut-off between PR negative and PR positive values.

The Recurrence Score result reflects the potential effect of 5 years of tamoxifen therapy, in addition to the tumor’s underlying prognosis. The addition of this quantitative ER Score may allow doctors to assess the potential magnitude of tamoxifen benefit for their patients.

Quantitative Hormone Receptor Analysis

The Oncotype DX assay uses RT-PCR to determine the RNA expression of the hormone receptor genes below. These results may differ from ER or PR results reported using other methods or reported by other laboratories¹.
The ER Score and the PR Score are also included in the calculation of the Recurrence Score.

The ER Score positive/negative cut-off of 6.5 units was validated from a study of 761 samples using the 1D5 antibody (immunohistochemistry) and 607 samples using the SP1 antibody (immunohistochemistry). The standard deviation for the ER Score is less than 0.5 units².

Clinical Experience:

For ER positive breast cancer, the magnitude of tamoxifen benefit increases as the ER Score increases from 6.5 to > 12.5.³
Please Note: The Average Rate of Distant Recurrence reported on Page 1 based on the Recurrence Score assumes 5 years of tamoxifen treatment and takes into account the magnitude of tamoxifen benefit indicated by the ER Score.

The PR Score positive/negative cut-off of 5.5 units was validated from a study of 761 samples using the PR636 antibody (immunohistochemistry) and another study of 607 samples using the PR636 antibody (immunohistochemistry). The standard deviation for the PR Score is less than 0.5 units.²

References:
1. ER Score based on quantitative ESR1 expression (estrogen receptor); PR Score based on quantitative PGR expression (progesterone receptor).
2. ASCO Breast Cancer Symposium 2007 Abstracts #87 by S.S. Badve et al., and #88 by F.L. Baehner et al.
3. ASCO Annual Meeting 2005 Abstract #510 by S. Paik et al.