Salivary duct carcinoma: A clinical and histologic review with implications for trastuzumab therapy

BACKGROUND: Salivary duct carcinoma (SDC) is an aggressive tumor of the head and neck with a poor prognosis. The objective was to study SDC and recommend the use of trastuzumab as adjuvant therapy. METHODS: A retrospective chart review of patients seen between 1993 and 2006 was performed. Tumor specimens were examined for HER-2 protein overexpression via immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) methods. RESULTS: Of the 7 patients with SDC, 57% had tumors arising in the parotid gland, the majority having facial nerve paralysis, 71% with nodal disease, and 43% having recurrence. All samples were HER-2 positive on IHC. Three patients had FISH-positive tumors, recurrent disease, and received trastuzumab therapy; 1 of the 3 died after 20 months and a second has shown disappearance of metastatic disease. CONCLUSIONS: Trastuzumab is effective in treating HER-2-positive breast cancer. Given immunohistochemical similarities between SDC and ductal carcinoma of the breast, patients with FISH-positive HER-2/neu SDC should be considered for trastuzumab therapy.