Patients undergo blood collection and buccal brushings periodically for pharmacokinetic and biomarker correlative studies. Archival tumor tissue is also evaluated for biomarkers, including epidermal growth factor receptor (EGFR) and HER-2/neu expression levels, EGFR polymorphisms and gene mutations (including RAS), levels of cellular proliferation and apoptosis, and RAS mutations by immunohistochemistry, mutation analysis, TUNEL assay, and polymerase chain reaction.