An online gene expression assay for determining adjuvant therapy eligibility in patients with stage 2 or 3 colon cancer

BACKGROUND: The decision whether to treat patients with non-metastatic colon cancer with adjuvant chemotherapy is determined by clinical staging, frequently resulting in over or undertreatment. METHODS: Gene expression data and clinical information from 232 stage 1–4 colon cancer patients were analysed to identify expression patterns predictive of recurrence. The signature was evaluated on an independent series of 60 stage 2 and 3 patients. Multivariate analyses were performed to assess the clinical utility of the assay. RESULTS: A 163-probe signature was able to stratify patients into high- and low-risk groups for disease-free survival (DFS) in both the training and validation series (stage 2: P⩽0.031, stage 3: P⩽0.057) and for disease-specific survival in the training series (stage 2: P=0.01, stage 3: P=0.0017). Multivariate analysis showed the classifier to be associated with approximately three- to fourfold increased risk of recurrence. CONCLUSIONS: The prognostic gene expression signature is able to stratify stage 2 and 3 colon cancer patients into groups with significant differences in 5-year DFS, information that may ultimately reduce deaths from colon cancer. Further validation work is required and at this stage the assay is available for evaluation at www.ChipDX.com.