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Routine pathologic parameters can predict Oncotype DX recurrence scores in subsets of ER positive patients: who does
K H Allison1, P L Kandalaft, C M Sitlani
1University of Washington Medical Center, Box 356100, Seattle, WA 98105, USA. kallison@uw.edu
Breast Cancer Research and Treatment
|March 4, 2011
Summary
Pathologic features like grade, progesterone receptor (PR) levels, and Ki67 can predict Oncotype DX Recurrence Scores (RS) in estrogen receptor-positive breast cancer. This may help in cases where Oncotype DX testing is costly or time-consuming.
Area of Science:
- Oncology
- Pathology
- Genomics
Background:
- The Oncotype DX assay is a RT-PCR-based test used to predict chemotherapy benefit in estrogen receptor (ER)-positive breast cancers.
- Routine pathologic parameters are often readily available and may correlate with Oncotype DX Recurrence Scores (RS).
Purpose of the Study:
- To investigate if routinely available pathologic parameters can predict Oncotype DX Recurrence Scores (RS) in subsets of ER-positive breast cancers.
- To identify specific patient subgroups where Oncotype DX testing might be unnecessary due to predictable RS based on pathology.
Main Methods:
- 173 breast cancers with available RS were analyzed, with 104 in a test set and 69 in a validation set.
- Pathologic characteristics (size, histologic type, Nottingham grade, lymphatic invasion) and biomarker expression (ER, PR, HER2, Ki67, etc.) were recorded.
- Statistical correlations and regression tree analysis were performed to identify predictors of RS.
Main Results:
- Nottingham grade, progesterone receptor (PR) levels, and Ki67 showed the strongest correlation with RS in the test set.
- Regression tree analysis identified grade and PR as key factors for segregating RS categories, with Ki67 providing additional value.
- Specific subsets were identified: Grade 1, strong PR, low Ki67 cancers were highly likely to have a low RS (73%), while Grade 3, low PR, high Ki67 cancers were highly likely to have a high RS (80%).
Conclusions:
- Pathologic parameters, specifically grade, PR expression, and Ki67 levels, can effectively predict low or high Oncotype DX Recurrence Scores in certain breast cancer subsets.
- In situations where cost and time are considerations, Oncotype DX testing may be reasonably assumed for patients with Grade 1/high PR/low Ki67 (likely low RS) or Grade 3/low PR/high Ki67 (likely high RS) breast cancers.
- This approach could potentially streamline treatment decisions and reduce unnecessary testing.