Salivary duct carcinoma: what is already known, and can we improve survival?

Salivary duct carcinoma is an aggressive malignancy with a high mortality rate, which phenotypically resembles high-grade breast ductal carcinoma. The parotid gland is the most common location. Standard treatment is surgery to the primary tumour together with post-operative radiotherapy. Despite this, there is a high rate of local recurrence, cervical nodal involvement and distant metastasis. Chemotherapy is currently considered only for end-stage, disseminated disease; however, current evidence indicates that chemotherapy used with radiotherapy may result in improved disease control and survival.Human epidermal growth factor receptor-2 is a proto-oncogene which is over-expressed in both breast ductal carcinoma and salivary duct carcinoma. Clinical studies of patients with metastatic breast cancer, using trastuzumab, a monoclonal antibody directed against human epidermal growth factor receptor-2, have shown significant efficacy in tumour response, resulting in improved survival. Such advances in immunohistochemistry, and in targeted immunotherapy for breast ductal carcinoma, should be applied to the treatment of salivary duct carcinoma.