Archived formalin-fixed paraffin-embedded (FFPE) tissue specimens collected at the time of diagnosis and associated histopathology reports were retrieved from the pathology departments where the diagnosis was made, and stored centrally. Personnel who performed histopathology reporting and scientific assays for biomarker analysis were blinded to patient identification and clinical outcomes.
Where available, a core of normal, colorectal adenoma, or colorectal tumour tissue (listed in order of preference) was extracted using a Beecher Mark II Tissue Arrayer (Beecher Instruments, Sun Prairie, WI, USA). Haematoxylin and eosin stained slides were used to guide the coring procedure.
For the first fifty cases (ordered consecutively by patient ID) where both colorectal tumour tissue and adjacent normal colorectal epithelial tissue were available, matching cores of tumour and normal tissue were extracted.
Where available, a core of normal, colorectal adenoma, or colorectal tumour tissue (listed in order of preference) was extracted using a Beecher Mark II Tissue Arrayer (Beecher Instruments, Sun Prairie, WI, USA). Haematoxylin and eosin stained slides were used to guide the coring procedure.
For the first fifty cases (ordered consecutively by patient ID) where both colorectal tumour tissue and adjacent normal colorectal epithelial tissue were available, matching cores of tumour and normal tissue were extracted.