Molecular Subtypes in Head and Neck Cancer [copy number]

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous disease whose underlying etiology has not been explained by traditional prognostic factors such as tumor site, stage, or histology. Although previous studies have shown that molecular subtypes of HNSCC exist, the benefit of such a classification scheme has not been fully realized. We show that molecular subtypes of HNSCC exist; that these subtypes have distinct patterns of chromosomal gain and loss, some of which affect canonical oncogenes and tumor suppressors; and that the subtypes are biologically and clinically relevant. These subtypes provide new insight into HNSCC etiology, as well as a valuable method for classifying HNSCC tumors. A total of 141 samples were considered. CEL files were subject to quality control (QC) procedures using the Affymetrix Genotyping Console, and arrays that produced contrast QC measurements above the default threshold of .4 were removed from subsequent analysis. The remaining 99 CEL files were processed with aroma, and log2 intensity ratios were produced using a pooled collection of normal samples as a reference. After segmenting the log2 ratios with DNAcopy, the resulting copy number profiles were subjected to manual review. Arrays that produced low quality copy number profiles were removed from subsequent analysis. Copy number values from chr1 - chr22 were considered.