AHNS series: Do you know your guidelines? Diagnosis and management of salivary gland tumors

Surgery of major salivary gland cancers: REFCOR recommendations by the formal consensus method

OBJECTIVE

To determine the role of surgery of the primary tumor site in the management of primary major salivary gland cancer.

MATERIAL AND METHODS

The French Network of Rare Head and Neck Tumors (REFCOR) formed a steering group, which drafted a non-systematic narrative review of the literature published on Medline, and proposed recommendations. The level of adherence to the recommendations was then assessed by a rating group, according to the formal consensus method.

RESULTS

Treatment of salivary gland tumor is mainly surgical. The gold standard for parotid cancer is a total parotidectomy, to obtain clear margins and remove all intraparotid lymph nodes. For low-grade tumors, partial parotidectomy with wide excision of the tumor is acceptable in the case of postoperative diagnosis on definitive histology. In the event of positive margins on definitive analysis, revision surgery should be assessed for feasibility, and performed if possible.

CONCLUSION

Treatment of primary major salivary gland cancer is based on surgery with clear resection margins, as far away as possible from the tumor. The type of surgery depends on tumor location, pathologic type and extension.

Preoperative cytopathological investigatory aids in the diagnosis of salivary gland lesions

Salivary gland lesions are a group of heterogeneous lesions inclusive of non-neoplastic and neoplastic lesions. History, clinical examination and preoperative investigations attempt to minimise the challenges faced in diagnosing these diverse lesions. Preoperative investigations include imaging and cytopathology. The advent of onsite evaluation methods to ensure sample adequacy and newer reporting systems that assign risk of malignancy has improved the sensitivity and specificity of cytopathology. The scope of this review is limited to the preoperative cytopathological investigations and the diagnostic challenges met in reporting salivary gland tumours.

Cytopathological analysis of salivary gland cancer: REFCOR recommendations by the formal consensus method

OBJECTIVE

To determine the indications for fine-needle cytology and the modalities of frozen section pathological analysis in the management of salivary gland cancer.

MATERIAL AND METHODS

The French Network of Rare Head and Neck Tumors (REFCOR) formed a steering group who drafted a narrative review of the literature published on Medline and proposed recommendations. The level of adherence to the recommendations was then assessed by a rating group according to the formal consensus method.

RESULTS

Fine-needle cytology is recommended as part of the diagnostic work-up for a major salivary gland tumor suspicious for malignancy. Fine-needle cytology should be performed after MRI to avoid artifacts. Frozen section analysis is recommended to confirm the malignant nature of the tumor, to adapt the extent of resection and to indicate neck dissection. Whenever possible, the entire tumor and adjacent salivary or periglandular tissue should be sent for frozen section analysis.

CONCLUSION

Fine-needle cytology and frozen section analysis play an essential role in the management of salivary gland cancers.

Don't SUMP it! Utility of PLAG1 immunocytochemistry in basaloid SUMP subcategory

BACKGROUND

Basaloid salivary gland neoplasm of uncertain malignant potential (B-SUMP) is an indeterminate diagnostic subcategory, with pleomorphic adenoma (PA) representing the most common benign neoplasm. Pleomorphic adenoma gene 1 (PLAG1) staining is frequently seen in PAs and could aid in distinguishing them from other basaloid neoplasms. The authors evaluated the utility of PLAG1 immunocytochemistry (ICC) in differentiating PAs from other basaloid neoplasms in smears and liquid-based cytology (LBC) specimens.

METHODS

In total, 45 B-SUMP cytology aspirates and corresponding surgical excision specimens were identified. PLAG1 immunostaining was performed in all aspirates and surgical excision specimens and was scored as positive (strong/diffuse), equivocal (focal/weak), or negative.

RESULTS

PLAG1 ICC was performed directly on 38 smears and seven LBC specimens. PLAG1 was positive in 29 of 45 cases (64%), whereas six of 45 (13%) were equivocal, and 10 of 45 (22%) were negative. PLAG1-positive aspirates included 26 (90%) PAs, two (7%) basal cell adenomas (BCAs), and one (3%) carcinoma ex-PA. PLAG1-equivocal aspirates included four (67%) PAs and two (33%) BCAs, whereas negative aspirates included five (50%) BCAs, four (40%) adenoid cystic carcinomas, and one (10%) metastatic adenosquamous carcinoma. The sensitivity, specificity, positive, and negative predictive values were 87%, 86%, 93%, and 75%, respectively. Diagnostic accuracy was 87%.

CONCLUSIONS

PLAG1 ICC is useful when positive (strong/diffuse) and can be reliably performed on smears and LBC specimens. PLAG1 was positive in most PAs and in a small subset of BCAs. Therefore, in the absence of atypical cytologic features, PLAG1-positive tumors could be diagnosed as benign, with a note favoring PA versus BCA. In contrast, PLAG1-negative/equivocal tumors should remain in the B-SUMP category.

Surgery of sublingual and minor salivary gland cancer: REFCOR recommendations by the formal consensus method

OBJECTIVE

To determine the indications and modalities for resection in the management of primary sublingual and minor salivary gland cancer, and the specific features of each primary location.

MATERIAL AND METHODS

The French Network of Rare Head and Neck Tumors (REFCOR) formed a steering group who drafted a narrative review of the literature published on Medline and proposed recommendations. The level of adherence to the recommendations was then assessed by a rating group, according to the formal consensus method.

RESULTS

Histological evidence (submucosal biopsy) is recommended before surgical treatment of minor salivary gland carcinoma. Surgical treatment is recommended, with optimal oncologic margins, adapted to anatomical factors, histologic type and grade and functional consequences, with reconstruction if necessary.

CONCLUSION

Treatment of primary minor salivary and sublingual gland cancer is surgical, with wide resection margins. The modalities of resection and reconstruction are highly dependent on tumor location, extension and histologic type.

The evolving landscape of salivary gland tumors

Salivary gland cancers are a rare, histologically diverse group of tumors. They range from indolent to aggressive and can cause significant morbidity and mortality. Surgical resection remains the mainstay of treatment, but radiation and systemic therapy are also critical parts of the care paradigm. Given the rarity and heterogeneity of these cancers, they are best managed in a multidisciplinary program. In this review, the authors highlight standards of care as well as exciting new research for salivary gland cancers that will strive for better patient outcomes.

Simultaneous Expression of PD-1 and PD-L1 in Peripheral and Central Immune Cells and Tumor Cells in the Benign and Malignant Salivary Gland Tumors Microenvironment

BACKGROUND

To investigate the differential expression of PD-1 and PD-L1 in salivary gland tumors (SGTs, malignant and benign subtypes) and determine their association with the clinicopathological characterization of the patients.

METHODS

The immunohistochemistry was used to examine PD-1 and PD-L1 expression in specimens from 83 patients with primary SGTs including salivary ductal carcinoma (SDC), adenoid cystic carcinoma (AdCC), acinic cell carcinoma (ACC), mucoepidermoid carcinoma (MEC), warthin's tumors (WT), poleomorphic adenoma (PA) and other subtypes.

RESULTS

The expression of PD-1 in peripheral and central immune cells (ICs) of MEC, and peripheral ICs of ACC was significantly higher than those with AdCC (P = 0.02, P = 0.02, P = 0.03, respectively). Interestingly, the expression of PD-1 was also observed in peripheral and central malignant tumor cells (TCs), particularly in SDC and ACC. Despite no significant difference in PD-L1 expression of TCs among malignant subtypes, the peripheral and central ICs of ACC and MEC were revealed to express PDL-1 significantly more than those with AdCC (P < 0.05). WTs were rich in PD-1/PD-L1 expressing ICs. However, the tumor microenvironment of PA generally had low levels of PD-1/PD-L1 expression. In general, the expression of PD-1 in peripheral and central TCs was found to be significantly higher in malignant tumors than in benign ones (P = 0.002 and P = 0.003, respectively).

CONCLUSION

The simultaneous presentation of PD-1 and PD-L1 in TCs and ICs of SGTs, their significant association with disease severity as well as the positive correlation between these immune checkpoints may suggest the therapeutic potential of anti-PD-1 and anti-PDL-1 combinational immunotherapy for SGTs.

Elective neck dissection in salivary gland malignancies: Systematic review and meta-analysis

We defined the occult nodal metastasis (ONM) rate of clinical node-negative salivary gland malignancies and examined the role of elective neck dissection (END). Meta-analysis querying four databases, from inception of databases to March 25th, 2020. Fifty-one studies with 11 698 patients were included. ONM rates were 64% for salivary ductal carcinoma (SDC), 51% for undifferentiated carcinoma, 34% for carcinoma ex-pleomorphic adenoma (CXPA), 32% for adenocarcinoma not otherwise specified (ANOS), 31% for lymphoepithelial carcinoma (LE), 20% for mucoepidermoid carcinoma, 17% for acinic cell carcinoma, and 17% for adenoid cystic carcinoma. T3/T4 tumors had a 2.3 times increased risk of ONM than T1/T2 tumors. High-grade tumors had a 3.8 times increased risk of ONM than low/intermediate-grade tumors. ONM rates were exceedingly high for T3/T4, high-grade, and undifferentiated, SDC, ANOS, CXPA, and LE tumors, indicating the potential role of END.

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.

Preoperative evaluation and treatment consideration of parotid gland tumors

BACKGROUND

The nature of parotid tumors often remains unknown preoperatively and final histopathology may reveal unexpected malignancy. Still, the use of fine-needle aspiration cytology (FNAC) and imaging varies in the management of these tumors.

METHODS

We evaluated the preoperative examinations and management of all 195 parotid gland tumors diagnosed within our catchment area of 1.6 million people during 2015.

RESULTS

Altogether 171 (88%) tumors were classified as true salivary gland neoplasms. FNAC showed no false malignant findings, but it was false benign in 5 (2.6%) cases. Preoperative MRI was utilized in 48 patients (25%). Twenty (10%) malignancies included 16 salivary gland carcinomas. Pleomorphic adenomas accounted for 52% of all adenomas. For 24 (40%) Warthin tumors, surgery was omitted.

CONCLUSION

The proportion of malignancies was lower than generally presented. Our proposed guidelines include ultrasound-guided FNAC with certain limitations. MRI is warranted in selected cases, but seems unnecessary routinely.

A 10-year review of primary major salivary gland cancers

Primary salivary gland cancers comprise a heterogeneous group of histological entities and represent less than 5% of head and neck malignancies. Surgical resection is the main treatment, and adjuvant radiotherapy is performed in selected cases. Chemotherapy is an option in metastatic or recurrent disease, with poor evidence. We aimed to review a 10-year experience of a cancer centre on major salivary gland cancers, focusing on clinical, pathological, treatment and patients' outcomes data. A total of 93 patients were identified, median age at diagnosis was 64 years (IQR, 23), and 51.6% were male. The parotid gland was the site of origin in 76.3% of cases. The most frequent histological type was salivary duct carcinoma (21.5%). All patients were submitted to surgery and adjuvant radiotherapy was performed in 74.2%. From 26 patients diagnosed with metastatic disease, 9 were treated with systemic therapy. At 8 years, disease-free survival was 54.6% and overall survival was 48.4%. Male sex, salivary duct carcinoma, stage pT3-4, stage pN2-3, high histologic grade, lymphovascular invasion and perineural invasion were negative prognostic indicators for disease-free survival and overall survival. Extracapsular spread was a negative prognostic indicator for overall survival. In the multivariable analysis, histological type-salivary duct carcinoma-kept significant negative impact in disease-free survival and high histologic grade in overall survival. The most frequent histological type was salivary duct carcinoma, which is estimated to represent only 9% of salivary tumours. Patients with salivary duct carcinoma relapsed more than other histological types. High histologic grade was a negative prognostic indicator for overall survival.

Salivary gland disease in the era of COVID-19 pandemic

Coronavirus disease 2019 (COVID‐19) pandemic forced significant changes in current approach to outpatient evaluation of common otolaryngology complaints as hospitals around the world are trying to limit the spread of the virus and to preserve health care resources. These changes raise a lot of questions regarding patient triage and treatment decisions in clinical situations when it is unclear if the workup and management can be postponed. In this communication, we present our approach to evaluation and triage of new patients with complaints concerning for salivary gland disease.

Prognostic Impact of PD-L1 Expression in Malignant Salivary Gland Tumors as Assessed by Established Scoring Criteria: Tumor Proportion Score (TPS), Combined Positivity Score (CPS), and Immune Cell (IC) Infiltrate

Background: Malignant neoplasms of the salivary glands are rare, and therapeutic options are limited. Results from recently published studies indicate a possible use for checkpoint inhibition in a subset of patients, but there are no established criteria for programme cell death ligand 1 (PD-L1) scoring in salivary gland carcinomas (SGCs). Methods: In this retrospective study, we present a cohort of 94 SGC patients with full clinical follow-up. We included 41 adenoid cystic carcinomas (AdCC), 21 mucoepidermoid carcinomas (MEC), 16 acinic cell carcinomas (ACC), 12 adenocarcinomas, not otherwise specified (AC, NOS), 2 epithelial-myoepithelial carcinomas (EMC), one salivary duct carcinoma (SDC), and one carcinoma ex pleomorphic adenoma (CA ex PA). Subsequent histopathological analysis was performed with special emphasis on the composition of the immune cell infiltrate (B-/T-lymphocytes). We assessed PD-L1 (SP263) on full slides by established scoring criteria: tumor proportion score (TPS), combined positivity score (CPS) and immune cell (IC) score. Results: We identified significantly elevated CD3+, TP, CP, and IC scores in AC, NOS compared to AdCC, MEC, and ACC. CPS correlated with node-positive disease. Moreover, AC, NOS displayed IC scores of 2 or 3 in the majority (67%) of cases (p = 0.0031), and was associated with poor prognosis regarding progression-free (PFS) (p < 0.0001) and overall survival (OS) (p < 0.0001). CPS correlated with strong nuclear or null p53 staining in AC, NOS but not in other SGCs. Long-lasting partial remission could be achieved in one AC, NOS patient who received Pembrolizumab as third-line therapy. Conclusions: The current study is the first to investigate the use of established scoring criteria for PD-L1 expression in malignant salivary gland tumors. Our findings identify unique characteristics for AC, NOS among the family of SGCs, as it is associated with poor prognosis and might represent a valuable target for immune checkpoint inhibition.

Real-World Outcomes and Prognostic Factors in Patients Receiving Nivolumab Therapy for Recurrent or Metastatic Head and Neck Carcinoma

Recently, a global phase III study demonstrated that nivolumab markedly improved patient outcomes in recurrent or metastatic head and neck carcinoma (RMHNC). However, the efficacy of nivolumab in patients who are ineligible for clinical trials is unknown. We investigated nivolumab efficacy in real-world patients and prognostic factors associated with the response to nivolumab. This study was conducted at 11 institutes associated with Kyoto University and its Affiliated Hospitals-Head and Neck Oncology Group. In total, 93 patients with RMHNC who received nivolumab between May 2017 and May 2018 were retrospectively reviewed. Objective response rate (ORR), overall survival, and progression-free survival (PFS) were evaluated. Univariate and multivariate analyses were performed to identify prognostic factors. The ORRs in patients with squamous cell carcinoma (SCC) and non-SCC were 21.8% and 0%, respectively. In patients with SCC and non-SCC, the 1-year PFS rates were 28.7% and 8.9%, respectively. The hazard ratio (HR) for risk of PFS events (SCC versus non-SCC) was 2.28 (95% confidence interval: 1.21–4.1; log-rank p = 0.007). Univariate and multivariate analyses revealed radiotherapy history, platinum-refractory carcinoma, and treatment-related adverse events (TRAEs) as important prognostic factors associated with PFS in patients with SCC. In a real-world setting, non-SCC and platinum-refractory carcinoma were associated with a poorer prognosis, and a history of radiotherapy to the primary tumor, and the occurrence of TRAEs were associated with a better prognosis. These findings could be useful for clinicians and patients when selecting a treatment strategy.