A Case of Successful Treatment with Trastuzumab for Advanced Salivary Duct Carcinoma in the Accessory Parotid Gland with Multiple Bone Metastasis

Abstract

Salivary duct carcinoma (SDC) is a highly malignant salivary gland tumor. Because of its low incidence, it has been impossible to standardize the optimal treatment strategies for SDC including adjuvant systemic therapy. Recently, it has been reported that SDC resembles mammary ductal carcinoma (DC). Over-expression of human epidermal growth factor type-2 (HER-2) protein has been shown in SDC as in mammary DC. We report herein on a successful treatment experience for a patient with advanced SDC using trastuzumab, a humanized monoclonal antibody.
A 56-year-old male was hospitalized with lumbalgia. Radiological examination indicated a tumor in the right accessory parotid gland and multiple metastatic tumors in the left skull base, ribs, lumbar vertebrae and sacral bone. Incisional biopsy of the right accessory parotid gland revealed SDC. Immunostaining for HER-2 was highly positive. He underwent concurrent radiation- and chemoradiotherapy (intensity-­modulated radiotherapy [IMRT 60 Gy], nedaplatin and docetaxel), which resulted in a poor response. Thereafter, trastuzumab was administered. He obtained a significantly effective response after 8 courses of treatment for the metastatic lesions.
In contrast to previous reports of a poor response to chemotherapy and poor survival rate of patients with SDC, our patient demonstrated that trastuzumab was a highly effective modality as a therapeutic choice for SDC.