BACKGROUND: The Oncotype DX Colon Cancer Assay is a new diagnostic test for 
determining the likelihood of recurrence in stage II colon cancer patients after 
surgical resection using fixed paraffin embedded (FPE) primary colon tumor 
tissue. Like the Oncotype DX Breast Cancer Assay, this is a high complexity, 
multi-analyte, reverse transcription (RT) polymerase chain reaction (PCR) assay 
that measures the expression levels of specific cancer-related genes. By 
capturing the biology underlying each patient's tumor, the Oncotype DX Colon 
Cancer Assay provides a Recurrence Score (RS) that reflects an individualized 
risk of disease recurrence. Here we describe its analytical performance using 
pre-determined performance criteria, which is a critical component of molecular 
diagnostic test validation.
RESULTS: All analytical measurements met pre-specified performance criteria. PCR 
amplification efficiency for all 12 assays was high, ranging from 96% to 107%, 
while linearity was demonstrated over an 11 log2 concentration range for all 
assays. Based on estimated components of variance for FPE RNA pools, analytical 
reproducibility and precision demonstrated low SDs for individual genes (0.16 to 
0.32 CTs), gene groups (≤ 0.05 normalized/aggregate CTs) and RS (≤ 1.38 RS 
units).
CONCLUSIONS: Analytical performance characteristics shown here for both 
individual genes and gene groups in the Oncotype DX Colon Cancer Assay 
demonstrate consistent translation of specific biology of individual tumors into 
clinically useful diagnostic information. The results of these studies 
illustrate how the analytical capability of the Oncotype DX Colon Cancer Assay 
has enabled clinical validation of a test to determine individualized recurrence 
risk after colon cancer surgery.