Cancers of major salivary glands

Presentation and outcomes of patients with clinically T1-2, N0 parotid mucoepidermoid carcinoma: The roles of elective neck dissection and adjuvant radiotherapy

Objectives

Examine the role of elective neck dissection (END) and adjuvant radiotherapy (RT) in early‐stage clinically N0 parotid mucoepidermoid carcinoma (MEC).

Methods

The study is a retrospective analysis of the National Cancer Database, 2004–2016. The study population included adult patients with MEC who underwent parotidectomy.

Results

A total of 1233 patients were included. Histopathology demonstrated well, moderately, and poorly differentiated MEC 47.12%, 39.98%, and 12.90% of the time, respectively. END was performed in 78.67% of patients, resulting in nodal upstaging in 4.43% and identification of extracapsular extension (ECE) in 0.72%. RT was utilized in 67.33% of patients with advanced pathological features. Neither END nor RT improved overall survival separately (p < 0.05) or combined (adjusted HR: 1.19, 95%CI: 0.52, 2.70, p = 0.68).

Conclusion

This study provides an epidemiological perspective regarding patients with clinically T1‐2, N0 MEC. There was no observed survival advantage with END and RT.

An Overview on the Histogenesis and Morphogenesis of Salivary Gland Neoplasms and Evolving Diagnostic Approaches

Simple Summary

Diagnosing salivary gland neoplasms (SGN) remain a challenge, given their underlying biological nature and overlapping features. Evolving techniques in molecular pathology have uncovered genetic mutations resulting in these tumors. This review delves into the molecular etiopatho-genesis of SGN, highlighting advanced diagnostic protocols that may facilitate the identification and therapy of a variety of SGN.

Abstract

Salivary gland neoplasms (SGN) remain a diagnostic dilemma due to their heterogenic complex behavior. Their diverse histomorphological appearance is attributed to the underlying cellular mechanisms and differentiation into various histopathological subtypes with overlapping fea-tures. Diagnostic tools such as fine needle aspiration biopsy, computerized tomography, magnetic resonance imaging, and positron emission tomography help evaluate the structure and assess the staging of SGN. Advances in molecular pathology have uncovered genetic patterns and oncogenes by immunohistochemistry, fluorescent in situ hybridization, and next–generation sequencing, that may potentially contribute to innovating diagnostic approaches in identifying various SGN. Surgical resection is the principal treatment for most SGN. Other modalities such as radiotherapy, chemotherapy, targeted therapy (agents like tyrosine kinase inhibitors, monoclonal antibodies, and proteasome inhibitors), and potential hormone therapy may be applied, depending on the clinical behaviors, histopathologic grading, tumor stage and location, and the extent of tissue invasion. This review delves into the molecular pathways of salivary gland tumorigenesis, highlighting recent diagnostic protocols that may facilitate the identification and management of SGN.

Anatomic extent of lymph node metastases as an independent prognosticator in node-positive major salivary gland carcinoma: A study of the US SEER database and a Chinese multicenter cohort

BACKGROUND

We aimed to explore whether the anatomic extent of lymph node metastases (AE-LNM) could independently predict prognosis of node-positive major salivary gland carcinoma (MaSGC).

METHODS

A total of 376 pathologically node-positive MaSGC patients were identified from the Surveillance, Epidemiology and End Results database and constituted the training cohort. Using the X-Tile program, these patients were divided into three groups based on AE-LNM degrees. Discrimination of overall survival (OS) and disease-specific survival (DSS) was evaluated and compared with the 8th American Joint Committee on Cancer (AJCC) pN classification. The results were externally validated by 220 patients in a Chinese multicenter cohort (Validation cohort).

RESULTS

Using the training cohort, AE-LNM was divided into Extent 1 (spread to parotid LNs or level I), Extent 2 (spread to level II-IV) and Extent 3 (spread to level V or bilateral LNs or rare LNs). Regarding both OS and DSS, the AE-LNM model revealed clear separation of survival curves, while the pN classification failed to discriminate the prognosis of pN1 and pN2 patients. When we incorporated both the AE-LNM model and AJCC pN classification into the same multivariate Cox analyses, AE-LNM was still an independent prognostic factor, while the AJCC pN classification lost its significance. These results were externally validated by the validation cohort.

CONCLUSION

AE-LNM is an independent nodal prognosticator for node-positive MaSGC and may have improved discriminative ability over the current AJCC pN classification. Integration of anatomic extent of LNM into the current AJCC N classification could be considered.

Incompletely treated malignancies of the major salivary gland: Toward evidence-based care

BACKGROUND

Unexpected malignancy is common in major salivary gland tumors due to variability of workup, creating challenging treatment decisions. The purpose of this study was to define treatment-related outcomes for patients with incompletely treated major salivary gland tumors.

METHODS

A retrospective cohort study was completed of patients with incompletely treated major salivary gland tumors. Tumor burden at presentation was established and treatment categorized. The Cox Proportional Hazards model was used to determine predictors of survival and failure.

RESULTS

Of the 440 included patients, patients with gross residual or metastatic disease had a worse overall survival (OS; P < .001). Presentation status was an independent predictor of OS on multivariate analysis (gross residual disease adjusted hazard ratio [HR_adjusted ] 2.55; 95% confidence interval [CI] 1.20-5.30; metastatic disease HR_adjusted 9.53; 95% CI 3.04-27.06).

CONCLUSION

Failure to achieve gross total resection during initial surgery resulted in worse OS. Adequate preoperative planning is required for initial surgical management to optimize tumor control and survival.

Nomograms for predicting long-term overall survival and cancer-specific survival in patients with major salivary gland cancer: a population-based study

In this study, we aimed to develop and validate nomograms for predicting long-term overall survival (OS) and cancer-specific survival (CSS) in major salivary gland cancer (MSGC) patients. These nomograms were developed using a retrospective cohort (N=4218) from the Surveillance, Epidemiology, and End Results (SEER) database, and externally validated using an independent data cohort (N=244). We used univariate, and multivariate analyses, and cumulative incidence function to select the independent prognostic factors of OS and CSS. Index of concordance (c-index) and calibration plots were used to estimate the nomograms’ predictive accuracy. The median follow-up period was 34 months (1–119 months). Of 4218 MSGC patients, 1320 (31.3%) died by the end of the follow-up; of these 1320 patients, 883 (20.9%) died of MSGC. The OS nomogram, which had a c-index of 0.817, was based on nine variables: age, sex, tumor site, tumor grade, surgery performed, radiation therapy and TNM classifications. The CSS nomogram, which had a c-index of 0.829, was based on the same nine variables plus race. External validation c-indexes were 0.829 and 0.807 for OS and CSS, respectively. Based on SEER database, we have developed nomograms predicting five- and eight-years OS and CSS for MSGC patients with perfect accuracy. These nomograms will help clinicians customize treatment and monitoring strategies in MSGC patients.

AKT3 drives adenoid cystic carcinoma development in salivary glands

Salivary gland cancer is an aggressive and painful cancer, but a rare tumor type accounting for only ~0.5% of cancer cases. Tumors of the salivary gland exhibit heterogeneous histologic and genetic features and they are subdivided into different subtypes, with adenoid cystic carcinomas (ACC) being one of the most abundant. Treatment of ACC patients is afflicted by high recurrence rates, the high potential of the tumors to metastasize, as well as the poor response of ACC to chemotherapy. A prerequisite for the development of targeted therapies is insightful genetic information for driver core cancer pathways. Here, we developed a transgenic mouse model toward establishment of a preclinical model. There is currently no available mouse model for adenoid cystic carcinomas as a rare disease entity to serve as a test system to block salivary gland tumors with targeted therapy. Based on tumor genomic data of ACC patients, a key role for the activation of the PI3K-AKT-mTOR pathway was suggested in tumors of secretory glands. Therefore, we investigated the role of Akt3 expression in tumorigenesis and report that Akt3 overexpression results in ACC of salivary glands with 100% penetrance, while abrogation of transgenic Akt3 expression could revert the phenotype. In summary, our findings validate a novel mouse model to study ACC and highlight the druggable potential of AKT3 in the treatment of salivary gland patients.

Tumor Differentiation as a Prognostic Factor for Major Salivary Gland Malignancies

Objective The effect of tumor differentiation on prognosis of major salivary gland malignancies is controversial. The aim of this study was to determine the effect of tumor differentiation on prognosis by stage in patients with major salivary gland malignancies and to analyze which patient factors are associated with tumor differentiation. Study Design and Setting Cross-sectional analysis of Surveillance, Epidemiology, and End Results (SEER) database. Subjects and Methods In total, 9810 patients who had a major salivary gland malignancy from 2004 to 2012 were identified using the SEER database. Patients with no staging information or no information on histologic differentiation were excluded. A total of 5366 patients were included in the study. For analysis, patients were categorized by American Joint Committee on Cancer (AJCC) stage and subdivided by tumor differentiation. Multivariate analysis was used to analyze the impact of tumor differentiation on survival, tumor location (parotid, submandibular, sublingual), and sex within each AJCC stage of disease. Results Data analysis demonstrated a significant difference in histologic differentiation by stage, with P < .0001. Within stages II, III, and IV, tumor differentiation was significantly associated with a decrease in survival. There was no significant difference in tumor differentiation between the parotid and submandibular gland. Conclusion For patients with stage II, III, and IV disease, tumor differentiation was an independent predictor of survival. This information can be useful when discussing prognosis and can potentially influence management of disease.

Androgen Receptor Signaling in Salivary Gland Cancer

Salivary gland cancers comprise a small subset of human malignancies, and are classified into multiple subtypes that exhibit diverse histology, molecular biology and clinical presentation. Local disease is potentially curable with surgery, which may be combined with adjuvant radiotherapy. However, metastatic or unresectable tumors rarely respond to chemotherapy and carry a poorer prognosis. Recent molecular studies have shown evidence of androgen receptor signaling in several types of salivary gland cancer, mainly salivary duct carcinoma. Successful treatment with anti-androgen therapy in other androgen receptor-positive malignancies such as prostate and breast cancer has inspired researchers to investigate this treatment in salivary gland cancer as well. In this review, we describe the prevalence, biology, and therapeutic implications of androgen receptor signaling in salivary gland cancer.

Myoepithelial carcinoma of the salivary gland: pathologic and CT imaging characteristics (report of 10 cases and literature review)

OBJECTIVE

To summarize the pathologic and computed tomography (CT) imaging characteristics of myoepithelial carcinoma in the salivary gland.

STUDY DESIGN

Ten patients with myoepithelial carcinoma of the salivary gland underwent enhanced CT scanning, and the pathologic and CT imaging features were evaluated, including the pathologic type, size, margin morphology, and enhancement pattern of the lesions.

RESULTS

Myoepithelial carcinoma had a multinodular or lobulated outline. The cut surfaces were gray-brown with no or incomplete capsules, and visible bleeding was observed in some cases. The pathologic cell type of the tumor was spindle-shaped, clear, plasmacytoid, or epithelioid cells or a mixture of cell types. Nonenhanced CT imaging showed an irregular lobulated or multinodular lesion with ill-defined margins and inhomogeneous attenuation and punctate calcification in a minority of the lesions. The enhanced CT imaging results revealed moderate and intense inhomogeneous enhancement, including cystic and slit-like regions with no enhancement, intense nodular enhancement, and small tortuous vessels in the arterial phase.

CONCLUSION

The pathologic features and CT imaging findings of myoepithelial carcinoma were characteristic, and familiarity with these imaging findings might aid in the diagnosis of this entity.