Salivary Duct Carcinoma of the Parotid: Outcomes with a Contemporary Multidisciplinary Treatment Approach

PSMA-targeted therapy for non-prostate cancers

Radioligand therapy (RLT) agents are demonstrating a crucial role in the clinical approach to aggressive malignancies such as metastatic castrate-resistant prostate cancer (m-CRPC). With the recent FDA approval of prostate-specific membrane antigen (PSMA)-targeted RLT for m-CRPC, the field has broadened its gaze to explore other cancers that express PSMA in the tumor parenchyma or tumor neovasculature. In this review article, we discuss current progress in the clinical use of PSMA RLTs in non-prostate cancers such salivary gland cancers, renal cell carcinoma, high grade glioma, and soft tissue sarcoma. We highlight early reports in small case series and clinical trials indicating promise for PSMA-targeted RLT and highlighting the importance of identifying patient cohorts who may most benefit from these interventions. Further study is indicated in non-prostate cancers investigating PSMA RLT dosimetry, PSMA PET/CT imaging as a biomarker, and assessing PSMA RLT safety and efficacy in these cancers.

Targeted treatment in a case series of AR+, HRAS/PIK3CA co-mutated salivary duct carcinoma

Background and purpose

A subgroup of salivary duct carcinoma (SDC) harbor overexpression of the androgen receptor (AR), and co-occurring mutations in the HRAS- and PIK3CA-genes. The impact of genomic complexity on targeted treatment strategies in advanced cancer is unknown.

Materials and methods

We analyzed molecular and clinical data from an institutional molecular tumor board (MTB) to identify AR+, HRAS/PIK3CA co-mutated SDC. Follow-up was performed within the MTB registrational study or retrospective chart review after approval by the local ethics committee. Response was assessed by the investigator. A systematic literature search was performed in MEDLINE to identify additional clinically annotated cases.

Results

4 patients with AR+ HRAS/PIK3CA co-mutated SDC and clinical follow-up data were identified from the MTB. An additional 9 patients with clinical follow-up were identified from the literature. In addition to AR overexpression and HRAS and PIK3CA-alterations, PD-L1 expression and Tumor Mutational Burden > 10 Mutations per Megabase were identified as additional potentially targetable alterations. Among evaluable patients, androgen deprivation therapy (ADT) was initiated in 7 patients (1 Partial Response (PR), 2 Stable Disease (SD), 3 Progressive Disease (PD), 2 not evaluable), tipifarnib was initiated in 6 patients (1 PR, 4 SD, 1 PD). One patient each was treated with immune checkpoint inhibition (Mixed Response) and combination therapies of tipifarnib and ADT (SD) and alpelisib and ADT (PR).

Conclusion

Available data further support comprehensive molecular profiling of SDC. Combination therapies, PI3K-inhibitors and immune therapy warrant further investigation, ideally in clinical trials. Future research should consider this rare subgroup of SDC.

Salivary gland cancer organoids are valid for preclinical genotype-oriented medical precision trials

Salivary gland cancers (SGCs) are heterogeneous tumors, and precision oncology represents a promising therapeutic approach; however, its impact on SGCs remains obscure. This study aimed to establish a translational model for testing molecular-targeted therapies by combining patient-derived organoids and genomic analyses of SGCs. We enrolled 29 patients, including 24 with SGCs and 5 with benign tumors. Resected tumors were subjected to organoid and monolayer cultures, as well as whole-exome sequencing. Organoid and monolayer cultures of SGCs were successfully established in 70.8% and 62.5% of cases, respectively. Organoids retained most histopathological and genetic profiles of their original tumors. In contrast, 40% of the monolayer-cultured cells did not harbor somatic mutations of their original tumors. The efficacy of molecular-targeted drugs tested on organoids depended on their oncogenic features. Organoids recapitulated the primary tumors and were useful for testing genotype-oriented molecular targeted therapy, which is valuable for precision medicine in patients with SGCs.

Lymph node ratio-based prognostic model for risk stratification and individualized adjuvant therapy for postoperative major salivary duct carcinoma

BACKGROUND

To investigate the value of lymph node ratio (LNR) for postoperative major salivary duct carcinoma (MSDC) and to establish a model for prognosis assessment and treatment optimization.

METHODS

Data of MSDC were retrieved in public database, and prognostic factors were identified by univariate and multivariate analyses. A nomogram and risk stratification system were constructed.

RESULTS

Four hundred and eleven eligible patients were included (training cohort vs. validation cohort: 287: 124). LNR ≥0.09 was associated with worse overall survival (OS). Age at diagnosis, sex, T stage, and LNR were identified as prognostic factors and integrated into nomogram. Low-risk patients were found to have better OS than high-risk patients. Furthermore, postoperative radiotherapy (PORT) significantly improved OS in the high-risk subgroup, but chemotherapy did not confer a long-term survival benefit.

CONCLUSIONS

A nomogram model integrating LNR could better assess postoperative prognosis and risk stratification in MSDC, and identify patients who might benefit from PORT to avoid overtreatment.

A population-based competing risk survival analysis of patients with salivary duct carcinoma

Background

Salivary duct carcinoma (SDC) is a rare malignancy with high risk of local recurrence and distant metastases of the salivary gland. This study was designed to summarize the clinical and pathological features and to further evaluate them as potential prognostic factors for SDC in the salivary gland.

Methods

Clinical data of 266 patients diagnosed with SDC between 2004 and 2015 were collected from the Surveillance, Epidemiology, and End Results (SEER) database. The prognostic factors affecting overall survival (OS) and cancer-specific survival (CSS) were determined by Kaplan-Meier analyses and Cox proportional hazards model. The nomogram was established to predict OS and CSS for SDC. The predictive accuracy of the nomograms was measured by concordance index (C-index).

Results

The 3- and 5-year OS of SDC patients were 67.41% and 47.86%, while the 3- and 5-year CSS were 84.6% and 60.7%, respectively. The primary site, T stage and M stage were identified as independent prognostic factors for OS by the multivariate analysis, whereas N stage, M stage, the presence of multiple primary carcinomas and the treatment modalities were identified as independent prognostic factors for CSS. The C-index values of the prognostic nomogram based the risk factors affecting SDC OS and CSS were 0.703 (0.646–0.760) and 0.771 (0.691–0.851), respectively.

Conclusions

SDC is an aggressive malignancy with a high proportion of advanced stage and lymph node metastases. Patients with increasing age, submandibular gland malignancy, advanced T stage, advanced N stage, advanced M stage, high lymph node ratio (LNR) and the presence of multiple primary carcinomas tend to have unfavorable outcomes. Radiotherapy or chemotherapy improve CSS remarkably. These factors will aid in effective therapeutic treatment modalities for SDC.

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.

Intensity Modulated Radiotherapy (IMRT) With Carbon Ion Boost in the Multimodal Treatment of Salivary Duct Carcinoma

Background: To assess outcomes and treatment related toxicity following intensity-modulated radiotherapy (IMRT) and a Carbon Ion Radiotherapy (CIRT) boost for salivary duct carcinoma (SDC).

Methods: Twenty-eight consecutive patients with SDC who underwent a postoperative (82%) or definitive (18%) radiation therapy between 2010 and 2017 were assessed in this retrospective single-center analysis. CIRT boost was delivered with median 18 Gy(RBE) in 6 daily fractions, followed by an TomoTherapy^®-based IMRT (median 54 Gy in 27 daily fractions). Treatment-related acute toxicity was assessed according to CTCAE Version 4.

Results: Tumors were most commonly located in the major salivary glands (n = 25; 89%); 23 patients (82%) received previous surgery (R0: 30%; R1: 57%; R2: 4%; RX: 19%). Median follow-up was 30 months. Four patients (14%) experienced a local relapse and 3 (11%) developed locoregional recurrence. The two-year local control (LC) and locoregional control (LRC) was 96 and 93%, respectively. Median disease-free survival (DFS) was 27 months, metastasis-free survival (MFS) was 69 months, and overall survival (OS) was 93 months. Acute grade 3 toxicity occurred in 11 patients (mucositis, dermatitis, xerostomia; n = 2 each (7%) were the most common) and 2 osteonecroses of the mandibular (grade 3) occurred. No patients experienced grade ≥4 toxicities.

Conclusions: Multimodal therapy approaches with surgery followed by IMRT and CIRT boost for SDC leads to good local and locoregional disease control. However, the frequent occurrence of distant metastases limits the prognosis and requires optimization of adjuvant systemic therapies.

The expression of PD-L1 in salivary gland carcinomas

Objective was to analyze the role of PD-L1 and its relation to demographic, patho-clinical and outcome parameters in salivary gland carcinoma (SGC) patients. Patients treated for salivary gland carcinomas between 1994 and 2010 were included. A retrospective chart review for baseline characteristics, pathohistological, clinical and outcome data was performed. Immunohistochemistry for PD-L1 was performed using tissue microarrays. PD-L1 expression was assessed in tumor cells and tumor-infiltrating immune cells (TIIC) and statistical analysis with regard to baseline and outcome data was performed. Expression of PD-L1 (by means ≥1% of the cells with PD-L1 positivity) was present in the salivary gland carcinoma cells of 17%, in the TIIC of 20% and in both tumor cells and TIIC of 10% the patients. PD-L1 expression in tumor cells and both tumor cells and TIIC was related to tumor grading (p = 0.035 and p = 0.031, respectively). A trend towards higher grading was also seen for PD-L1 expression in TIICs (p = 0.058). Patients with salivary duct carcinomas and PD-L1 expressing TIICs showed a significantly worse DFS and OS (p = 0.022 and p = 0.003, respectively), those with both tumor cells and TIIC expressing PD-L1 a significantly worse DFS (p = 0.030). PD-L1 expression is present in 17% and 20% of salivary gland carcinoma cells and TIIC. Ten percent of the patient showed a PD-L1 positivity in both tumor cells and TIIC. This is related to high tumor grading and therefore might be a negative prognostic factor.

Salivary duct carcinoma: Prospective multicenter study of 61 cases of the Réseau d'Expertise Français des Cancers ORL Rares

BACKGROUND

The purposes of this study were to describe the characteristics of a prospective multicenter series of patients with salivary duct carcinoma and to investigate prognostic factors.

METHODS

Patients included for salivary duct carcinoma between 2009 and 2016 in the Réseau d'Expertise Français des Cancers ORL Rares (REFCOR) database were selected. Immunohistochemical analyses were performed.

RESULTS

Sixty-one patients were included in this study. The primary site was the parotid gland in 90% of the cases. Fifty-seven percent of the tumors were stage IV, 65% of patients had lymph node involvement, and 10% had metastases. Tumors showed androgen receptor (89%) and human epidermal growth factor receptor 2 (HER2)/neu (36%). Ninety-four percent of patients underwent surgery and 86% had postoperative radiotherapy. Six patients were treated with targeted therapies. The 3-year overall survival (OS) was 74% and the 3-year disease-free survival (DFS) was 44%. Tumor stages III to IV reduced DFS (hazard ratio [HR] 4.3; P = .04). The N2/3 class reduced distant metastasis-free survival (HR 7.3; P = .007).

CONCLUSION

Salivary duct carcinoma prognosis is poor and is correlated with tumor stage and lymph node classification. Androgen receptor and HER2/neu should be tested as they offer the possibility of targeted therapies.

Salivary duct carcinoma: evaluation of treatment and outcome in a tertiary referral institute

PURPOSE

The aggressive behavior of salivary duct carcinoma (SDC) necessitates an aggressive treatment strategy, including surgery and radiotherapy (RT). We evaluated practice patterns and treatment outcomes in patients with SDC treated in our Institute.

METHODS

Patients with SDC of the parotid or submandibular gland treated with curative intention in our Institute from 1998 until 2016 were reviewed. Our diagnostic workup and treatment strategy were evaluated together with treatment outcomes.

RESULTS

Fifteen patients with SDC were included. Staging included MRI and ultrasound-guided fine needle aspiration cytology. Only in a minority (20%) of patients, the preoperative diagnosis of SDC was raised due to positive immunohistochemical staining for the androgen receptor (AR) on cytology. All patients were treated with (sub)total resection of the salivary gland and 53% underwent a therapeutic neck dissection. All patients except one received postoperative RT. Immunohistochemical staining was found positive for AR (100%) and human epidermal growth factor receptor 2 (HER2/neu) (13%). No local recurrences occurred. Regional and distant failure rates were 20% and 40%, respectively.

CONCLUSIONS

Excellent local control rates can be achieved with extensive (local) surgical treatment and postoperative RT. In case of lymph node metastases, a neck dissection with adjuvant postoperative RT is warranted. In patients with node-negative disease, a less aggressive approach for the neck seems feasible to reduce treatment-related morbidity.

Cervical Lymph Node Metastatic Status and Adjuvant Therapy Predict the Prognosis of Salivary Duct Carcinoma

PURPOSE

Salivary duct carcinoma (SDC) is an aggressive malignancy that is not yet fully understood. We designed the present retrospective study to investigate the factors affecting the prognosis of SDC and the effects of adjuvant therapies on the clinical outcomes of patients.

MATERIALS AND METHODS

Patients with SDC treated surgically from 2006 to 2016 were enrolled in the present retrospective cohort study. The demographic data, clinical pathologic characteristics, and follow-up results were recorded. The prognostic indicators of overall survival (OS), locoregional failure-free survival (LRFFS), and distant metastasis-free survival (DMFS) were analyzed using the Kaplan-Meier method and the Cox proportional hazard model.

RESULTS

The study sample included 66 patients, most of whom were male (81.8%). The 5-year OS, LRFFS, and DMFS for all patients was 52.5%, 63.9%, and 51.3%, respectively. Univariate analysis showed that stage N2-N3, lymph node involvement of levels IV and V, 8 or more positive lymph nodes, and extranodal extension were all negative prognostic indicators for OS. The only significant indicator on multivariate analysis was the number of positive lymph nodes. Multivariate analysis revealed that extracapsular invasion and no adjuvant radiotherapy were risk factors for LRFFS. In contrast, lesions involving both glands and 8 or more positive lymph nodes were prognostic factors for DMFS. Further subgroup analysis showed that radiotherapy was only useful for patients with locally advanced lesions for local control.

CONCLUSIONS

Cervical lymph node metastatic status is an important factor in predicting the prognosis of SDC patients. Adjuvant radiotherapy is useful for local control, especially for patients with stage T4 disease but does not benefit OS and DMFS.

Salivary duct carcinoma: An aggressive salivary gland malignancy with opportunities for targeted therapy

Salivary duct carcinoma (SDC) is a rare, aggressive salivary malignancy that is often diagnosed at an advanced stage. Previously, little was known about outcomes of this disease due to its rarity. In the past several years, much has been learned about salivary duct carcinoma after publication of outcomes from several large single-institution series and national database searches. Recent studies of genomic alterations have helped elucidate the biology and pathogenesis of this aggressive disease. Here we review outcomes of the disease, effects of treatment, prognostic factors, and genomic alterations in SDC. Studies of targeted therapy and promising future directions are also discussed.

Margin Analysis: Malignant Salivary Gland Neoplasms of the Head and Neck

There are no established protocols for the optimum surgical margin required for salivary gland malignancies. Factors including histologic diagnosis and TNM stage have been shown to be important in prognosis and survival outcome and mandate special consideration of margin size. Salivary cancers are treated differently at different anatomic sites, and different histologic types show a propensity for major or minor glands. Low-grade malignancies are treated with soft tissue margins of 1 cm or less. The facial nerve is preserved unless infiltrated and encased. Adenoid cystic carcinoma and carcinoma ex pleomorphic adenoma require more complex planning to obtain negative margins.