Analysis of malignancy predictors for oxyphile thyroid tumors.

PURPOSE In contrast to other thyroid carcinomas it is difficult to establish a correct preoperative diagnosis for oxyphile carcinoma of the thyroid. In this study we looked for predictive malignancy factors in order to enable surgeons to choose operative treatment and to perform an adequate operation for each patient with an oxyphile neoplasm of the thyroid. METHODS In this retrospective study we have analyzed the medical files of all patients with oxyphile tumors of the thyroid operated between 1999 and 2008 in our institution. A total of 256 patients were included and divided into oxyphile adenomas (142) and carcinomas (114) on the basis of their definite histopathological diagnosis. The most important demographic and clinical characteristics were analyzed by univariate and multivariate logistic regression analysis. RESULTS Univariate analysis showed that male gender, thyroglobulin concentrations ≥300 ng/ml and tumor diameter >30 mm were significantly more frequent in patients with oxyphile carcinoma compared to patients with oxyphile adenoma, while coexisting Hashimoto thyreoiditis and positive AntiTPO antibodies appeared significantly less frequent in the carcinoma group. All variables with a p value <0.1 in the univariate test were subjected to multivariate regression analysis in which elevated preoperative thyroglobulin concentrations (≥300 ng/ml) was shown as the only independent predictive factor for oxyphile thyroid carcinomas (OR=5.88, 95% CI 2.78-12.05, p=0.001). CONCLUSIONS Preoperative thyroglobulin concentration is an independent predictor of malignancy for oxyphile thyroid carcinomas.