Treatment outcomes of patients with salivary duct carcinoma undergoing surgery and postoperative radiotherapy

Clinical value of adjuvant therapy on the prognosis of ductal carcinoma of the major salivary gland: a large-scale cohort study

PURPOSE

To explore the clinical characteristics, prognostic factors, and value of adjuvant therapy for major salivary duct carcinoma (SDC).

METHODS

Data of SDC patients who received surgery was obtained from Surveillance, Epidemiology, and End Results (SEER) database (2004-2016). Kaplan-Meier and Cox regression analyses were performed to assess prognostic factors. Propensity score matching (PSM) was done to evaluate the clinical value of adjuvant therapy.

RESULTS

A total of 287 patients were enrolled. The 5-year overall survival (OS) and disease-specific survival (DSS) rates were 53.8% and 70.8%, respectively. In the univariate analysis, tumor size, T, N, TNM staging, SEER combined staging, number of regional lymph nodes examined, and number of positive lymph nodes were associated with OS and DSS. Age and primary surgical methods were also related to OS. Among patients with negative lymph nodes, patients with tumor size > 4 cm had significantly worse prognosis (P = 0.009). Multivariate analysis showed that age > 75 years, T3-4, and positive lymph nodes were independent risk factors for SDC. After PSM, the prognostic factors were age, tumor site, and T and N stage. Postoperative radiotherapy could improve OS in patients with tumor size > 4 cm (P = 0.049).

CONCLUSIONS

Advanced age, submandibular gland lesions, T3-4 stage, and lymph node involvement were independent prognostic factors for SDC. In patients with tumors > 4 cm, adjuvant radiotherapy improved the OS of SDC patients.

Ex Vivo Drug Screening Informed Targeted Therapy for Metastatic Parotid Squamous Cell Carcinoma

The purpose of ex vivo drug screening in the context of precision oncology is to serve as a functional diagnostic method for therapy efficacy modeling directly on patient-derived tumor cells. Here, we report a case study using integrated multiomics ex vivo drug screening approach to assess therapy efficacy in a rare metastatic squamous cell carcinoma of the parotid gland. Tumor cells isolated from lymph node metastasis and distal subcutaneous metastasis were used for imaging-based single-cell resolution drug screening and reverse-phase protein array-based drug screening assays to inform the treatment strategy after standard therapeutic options had been exhausted. The drug targets discovered on the basis of the ex vivo measured drug efficacy were validated with histopathology, genomic profiling, and in vitro cell biology methods, and targeted treatments with durable clinical responses were achieved. These results demonstrate the use of serial ex vivo drug screening to inform adjuvant therapy options prior to and during treatment and highlight HER2 as a potential therapy target also in metastatic squamous cell carcinoma of the salivary glands.

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.

Adjuvant therapy in the management of operable salivary duct carcinoma: correlating evidence with a retrospective review

Background:

Salivary duct carcinoma (SDC) is an extremely rare and aggressive subtype of salivary gland cancer with high morbidity and mortality and poor response to treatment. The current options of treatment include radical surgery followed by radiotherapy (RT) with or without chemotherapy. The aim of this study was to analyse the patterns of recurrences, possible predictors of outcome and role of RT in a cohort of patients with non-metastatic SDC.

Methods:

A retrospective review of patients treated between 2010 and 2019 with histologically proven non-metastatic SDC was conducted.

Results:

Sixteen patients were included in the series. Median follow-up was 25 months. Progression-free survival (PFS) and overall survival (OS) at 12 months were 61% and 80%, respectively. Seven out of the 16 patients had disease progression, distant metastases being most frequent. Four patients died due to disease progression. PFS was significantly worse for patients with pathological neck node positivity (p = 0·036) and peri-parotid nodes (p = 0·007). Local control was significantly associated with RT (p = 0·011). Addition of any chemotherapy, regardless of either concurrent or adjuvant, had no impact on the PFS or OS. Pathological neck node positivity with nodal stage of N2 or higher correlated significantly with worse OS (p = 0·031).

Conclusion:

Salivary ductal carcinoma is an aggressive malignancy with high metastatic potential. Inferior prognosis was observed among patients who had metastatic deposits in either cervical nodes or peri-parotid nodes on histopathology. As systemic failures are more predominant among these patients, larger prospective trials are needed to formulate an optimum strategy for choice and sequencing of first-line systemic therapy.

A Case of Salivary Duct Carcinoma Intracranial Invasion due to Perineural Invasion Through the Facial Nerve

BACKGROUND

Salivary duct carcinoma (SDC) is a rare parotid tumor that often develops as a rapidly growing mass with a poor prognosis. It has a high rate of distant metastases, sometimes with infiltration along nerves. We describe a case of SDC that originated outside the cranium and extended into the cranium along the path of the facial nerve.

CASE DESCRIPTION

A 74-year-old man underwent magnetic resonance imaging at a local hospital, which revealed a tumor in the left internal acoustic canal; the patient was referred to our department. A left facial schwannoma was suspected, and magnetic resonance imaging was performed again 6 months later. Rapid tumor growth was confirmed, and the tumor was resected. The tumor displayed atypical epithelial cells with comedo necrosis and cribriform structure and was diagnosed as SDC. All residual intracranial tumors were removed using the middle fossa approach. The tumor, which was considered to be a primary tumor, was found near the stylomastoid foramen, and it was removed with the parotid gland. Five months after the initial surgery, metastasis to the trigeminal nerve was observed, and this was removed using a retrosigmoid approach, followed by radiation therapy.

CONCLUSIONS

All 4 surgical specimens of this case were presented, and the path of tumor progression was examined in detail. Although the primary lesion was small, intracranial invasion along the facial nerve occurred. SDC should be considered as a tumor that can extend into the cranium, even with a small primary lesion.