A low percentage of HER-2 amplification whereas indicates poor prognosis in salivary carcinoma ex pleomorphic adenoma: a study of 140 cases.

BACKGROUND: Human epidermal growth factor receptor 2 (HER-2) has been found in many malignant tumours including salivary malignancy. HER-2-targeted therapy has been applied in the treatment of HER-2-overexpressing carcinoma. The aim of this study was to determine the status of HER-2 in salivary invasive carcinoma ex pleomorphic adenoma (ICXPA) in a relatively large Chinese sample, which may provide HER-2-targeted therapy with profound support in the future. METHODS AND RESULTS: We collected 140 ICXPAs and their related clinicopathological and follow-up data. All cases were examined for HER-2 expression by immunohistochemistry and gene amplification by fluorescence in situ hybridization, if necessary. The study showed that the ratio of HER-2 positivity was only 25% (35/140) in all cases, but the positive ratio in ICXPAs with luminal differentiation for malignant component (32/79, 40.5%) was much higher than that in cases with non-luminal differentiation (3/61, 4.9%). The overexpression of HER-2 was closely associated with gender, histological grade and N stage. HER-2-positive tumours conferred short overall survival time (P = 0.036) and short disease-specific survival time (P = 0.042) in patients, but HER-2 status was not an independent predictor of prognosis. CONCLUSIONS: Human epidermal growth factor receptor 2 amplification is significantly associated with cell differentiation of the malignant component in ICXPA and it implies an unfavourable prognosis. Although HER-2 positivity is not common in the tumour, HER-2-targeted therapy for those HER-2-positive patients is still worth expecting.