What is a prognostic test?
A prognostic test estimates a likely disease outcome1
. Examples of disease outcomes in breast cancer are distant recurrence, disease progression or death. For a solely prognostic test, treatment effect does not depend on the test result.1
What is a predictive test?
A chemo-predictive test predicts the effect of chemotherapy on a disease outcome, identifying patients who are more and less likely to benefit from the treatment.
The Oncotype DX Breast Recurrence Score® test meets the criteria for a predictive test/biomarker:1, 4, 11
- Treatment effect differs for biomarker-positive patients (i.e., high risk by Recurrence Score® result) compared with biomarker-negative patients (i.e., low risk by Recurrence Score result).
- The formal test for an interaction between the biomarker result and treatment group on disease outcome is statistically significant.
- The interaction of the biomarker result and treatment group on disease outcome was assessed in data from a clinical trial where patients were randomized to treatment group.
The Oncotype DX Breast Recurrence Score® test is the only test validated as both prognostic of disease outcome and predictive of chemotherapy benefit in HR+, HER2- early invasive breast cancer patients3-4, 9, 11. Validation of the Oncotype DX test was conducted according to published standards with a formal test of interaction from a clinical trial where patients were randomized to treatment group1, 4, 11. Other multigene assays and clinical-pathologic features have not provided evidence for chemo-prediction.12-14
Only multi-gene assay can inform about treatment benefit for an individual patient1, 4, 11
Treatment decisions in early breast cancer have historically been based on prognostic factors alone (grade, size and age). The Oncotype DX test adds information to help guide chemotherapy decisions.
A test predictive of chemotherapy benefit, which provides additional information on prognosis, can help avoid over- and under treatment with chemotherapy.4, 11, 15
How does the Oncotype DX test compare to prognostic-only tests?
Multigene assays are not interchangeable; studies show high rates of discordance across all multigene assays (>40% discordance rate)2. Other multigene assays analysing different genes were developed to estimate disease prognosis only; hence, such variability would be expected when compared to the Oncotype DX test, the only assay proven to predict chemotherapy benefit.4,11 Similarly, substantial discordance has been observed between prognostic-only parameters (e.g. tumour grade, Ki67 level and nodal status) and the Oncotype DX test4,16; only the Oncotype DX test has been validated for the purpose of identifying patients who may benefit from chemotherapy and those who may not, rather than extrapolating that benefit from a prognostic-only parameter.13, 14
The Oncotype DX Breast Recurrence Score assay vs. other multigene assays: 40%–60% discordance in risk classifications2
a Overall discordance=any difference in risk classification between the Recurrence Score results and other assays
b Study used non-standard Recurrence Score cut points for comparison of Recurrence Score vs. MMP
Multigene assays for breast cancer are not interchangeable
RCT = randomised clinical trial; ET = endocrine therapy; CT = chemotherapy
While all four multigene assays provide prognostic information, only the Oncotype DX Breast Recurrence Score assay can identify patients who will benefit and those who can be spared chemotherapy.4, 11