Gene Expression Provides an Individualized Recurrence Assessment
The Oncotype DX® Colon Recurrence Score uses an algorithm to generate a Colon Recurrence Score result that is based on a panel of 12 genes: seven genes associated with recurrence and five genes used to normalize gene expression. The Oncotype DX Colon Recurrence Score analyzes the expression of the aforementioned panel of 12 genes from a formalin-fixed paraffin embedded tumor (FPET) specimen using a technique called reverse transcriptase-polymerase chain reaction (RT-PCR).
Why RT-PCR was chosen for the Oncotype DX Colon Recurrence Score
A high-throughput, real-time RT-PCR method was developed to analyze the expression of select genes simultaneously. This method is sensitive, precise, reproducible, and has a wide dynamic range. RT-PCR is a mature technology that is routinely utilized in several clinical applications, including the broadly adopted Oncotype DX Breast Recurrence Score as well as viral load testing for HIV. The Oncotype DX Colon Recurrence Score standardized testing methods have been optimized to minimize variability due to:
- Tissue preparation method: formalin-fixed paraffin-embedded (FPET) vs. fresh frozen
- Tumor block age, storage and variability in preparation
- Heterogeneity within and between FPET blocks
- Heterogeneity with respect to enriched tumor and non-tumor areas within an FPET block
12-Gene Panel Used to Calculate Colon Recurrence Score Result
The Oncotype DX Colon Recurrence Score gene panel and Recurrence Score result calculation were validated in a large, independent, multicenter clinical trial (QUASAR). The Colon Recurrence Score result contains gene groups consistently identified in the 1,851 patients from the development studies, and the validation of the Colon Recurrence Score result in QUASAR provides strong support for biological relevance. The endpoints and analysis plan were prospectively defined. The results of these studies were presented in the general session for Colorectal Cancer at ASCO® 2009 and published.
Next: The Colon Recurrence Score Report
- In clinical studies, the Colon Recurrence Score result demonstrated a consistent and significant relationship to colon cancer recurrence.
- The Colon Recurrence Score result is calculated from the expression of 7 cancer-related genes, and 5 reference genes used to normalize the expression of the cancer-related genes.
- The gene groups included in the Colon Recurrence Score result are representative of the two key biological pathways (cell cycle genes and stromal genes) identified in the 4 development studies.