Affymetrix array expression data from colon polyps

The tubular adenoma sample cohort (accrued by Janssen Pharmaceuticals) consisted of 127 high-risk baseline adenoma samples acquired retrospectively by Avaden Biosciences. High risk patients are defined here as presenting a tubular adenoma ? 10mm, 3 or more adenomas, adenomas with villous histology or adenomas showing high-grade dysplasia based on Lieberman et al. Patients with familial adenomatous polyposis (FAP) and Lynch syndrome were excluded. All patients received at least one baseline colonoscopy for which clinical and pathological records were available. Adenoma tissue was available as archival, formalin-fixed, paraffin-embedded (FFPE) blocks. Expression dataset (N=61 samples) for the colon polyps was derived using Affymetrix Array platform (HT HG-U133 Plus PM) and was processed using affy package with Robust Multichip Average (RMA) normalization.