Adjuvant Treatment of the Salivary Duct Carcinoma with Her2 Overexpression

Malignant salivary gland tumors form 11% of all head and neck tumors. Salivary duct carcinoma (SDC) of the parotid gland is an uncommon and highly aggressive tumor accounting for 2% of all salivary gland malignancies. The fourth edition of the WHO Classification of Head and Neck Tumors reported global annual incidence of 0.4–2.6/100,000 people. Standard treatment for SDC is wide surgical resection along with lymph node dissection followed by adjuvant radiation therapy. The role of adjuvant chemotherapy is not known. Here, we present a case of an SDC of the parotid gland in a 55-year-old female. She presented with a painless swelling behind her right ear. Surgery was performed, and total right parotidectomy was done along with selective neck dissection (levels II, III, VA). The pathology report concluded that it was a G3 (poorly differentiated) SDC (micropapillary variant) with lymphovascular and perineural invasion. The clinical stage of the disease was T4aN2bM0. Adjuvant therapy consisted of concurrent radiation (TD 66 Gy) and chemotherapy with weekly paclitaxel (45 mg/m²), carboplatin (AUC 1.5), and trastuzumab (2 mg/kg; THC) for 6 weeks followed by 4 cycles of THC every 3 weeks. Adjuvant trastuzumab was continued for a total of 1 year. She is still without the evidence of the disease 7 years later. The consensus regarding the use of adjuvant chemotherapy does not exist. Based on all the data that have been presented before, the conclusion is that we need new treatment modalities to improve the outome of this aggressive disease.