AbstractBackgroundThis study assessed the presence of oxidative damage and lipid peroxidation in thyroid neoplasia.MethodsUsing tissue microarrays and immunohistochemistry, we assessed levels of DNA damage (8‐oxo‐dG) and lipid peroxidation (4‐HNE) in 71 follicular thyroid adenoma (FTA), 45 papillary thyroid carcinoma (PTC), and 17 follicular thyroid carcinoma (FTC) and matched normal thyroid tissue.ResultsCytoplasmic 8‐oxo‐dG and 4‐HNE expression was significantly higher in FTA, FTC, and PTC tissue compared to matched normal tissue (all p values < .001). Similarly, elevated nuclear levels of 8‐oxo‐dG were seen in all in FTA, FTC, and PTC tissue compared to matched normal (p values < .07, < .001, < .001, respectively). In contrast, a higher level of 4‐HNE expression was detected in normal thyroid tissue compared with matched tumor tissue (p < .001 for all groups). Comparing all 3 groups, 4‐HNE levels were higher than 8‐oxo‐dG levels (p < .001 for all groups) except that cytoplasmic levels of 8‐oxo‐dG were higher than 4‐HNE in all (p < .001). These results were independent of proliferation status.ConclusionHigh levels of DNA damage and lipid peroxidation in benign and malignant thyroid neoplasia indicates this damage is an early event that may influence disease progression. © 2009 Wiley Periodicals, Inc. Head Neck, 2010