Data Set for the Reporting of Carcinomas of the Major Salivary Glands: Explanations and Recommendations of the Guidelines From the International Collaboration on Cancer Reporting

Metastatic cutaneous squamous cell carcinoma accounts for nearly all squamous cell carcinomas of the parotid gland

Primary squamous cell carcinoma of the parotid gland (pSCCP) has long been recognized as a separate entity and is included in the WHO classifications of salivary gland tumors. However, it is widely accepted among head and neck pathologists that pSCCP is exceptionally rare. Yet, there are many publications describing series of pSCCP and data from SEER and other cancer register databases indicate erroneously an increasing incidence of pSCCP. Importantly, pSCCP and metastatic (secondary) squamous cell carcinoma to the parotid gland (mSCCP) have nearly identical histological features, and the diagnosis of pSCCP should only be made after the exclusion of mSCCP. Moreover, all of the histological diagnostic criteria proposed to be in favor of pSCCP (such as, for example, dysplasia of ductal epithelium) can be encountered in unequivocal mSCCP, thereby representing secondary growth along preexistent ducts. Squamous cell differentiation has also been reported in rare genetically defined primary parotid carcinomas, either as unequivocal histological squamous features (e.g., NUT carcinoma, mucoepidermoid carcinoma), by immunohistochemistry (e.g., in NUT carcinoma, adamantinoma-like Ewing sarcoma, basal-type salivary duct carcinoma, mucoepidermoid carcinoma), or a combination of both. Another major issue in this context is that the International Classification of Diseases (ICD) coding system does not distinguish between primary or metastatic disease, resulting in a large number of patients with mSCCP being misclassified as pSCCP. Immunohistochemistry and new molecular biomarkers have significantly improved the accuracy of the diagnosis of many salivary gland neoplasms, but until recently there were no biomarkers that can accurately distinguish between mSCCP and pSCCP. However, recent genomic profiling studies have unequivocally demonstrated that almost all SCCP analyzed to date have an ultraviolet light (UV)-induced mutational signature typical of mSCCP of skin origin. Thus, mutational signature analysis can be a very useful tool in determining the cutaneous origin of these tumors. Additional molecular studies may shed new light on this old diagnostic and clinical problem. This review presents a critical view of head and neck experts on this topic.

The Number of Positive Lymph Nodes Instead of Extranodal Extension and Nodal Diameter is an Independent Predictor of Survival and Treatment Outcome of High-Grade Parotid Gland Carcinoma

BACKGROUND

There is emerging evidence that current 8th edition of the American Joint Committee staging system is not sensitive enough to predict parotid gland carcinoma (PGC) survival outcomes.

PURPOSE

The present study aimed to analyze pathological nodal factors related to survival and treatment outcomes in a cohort of patients surgically treated with PGC.

STUDY DESIGN, SETTING, SAMPLE

We performed a retrospective cohort study of consecutive patients surgically treated with PGC at the authors' institution from January 1993 to December 2018. The inclusion criteria were as follows: confirmed high-grade parotid gland malignancy on histopathology first surgical treatment of the parotid cancer with neck dissection with curative intent at the study clinic; and sufficient data for review. The exclusion criteria were previous treatment in another institution, low-grade carcinomas, cases where neck dissection was not performed, incurable local disease and distant metastases at the time of first diagnosis, and patients lost to follow-up.

PREDICTOR VARIABLE

Predictor variable comprised pathological nodal factors grouped as the number of cervical node metastases, extranodal extension (ENE), largest diameter of nodal metastasis, and involvement of parotid lymph nodes.

MAIN OUTCOME VARIABLES

Outcomes evaluated were overall survival (OS), disease-specific survival (DSS), recurrence-free survival (RFS), locoregional recurrence-free survival, and distant metastasis-free survival (DMFS). OS was calculated from the day of biopsy or definitive surgery to the last known hospital follow-up date or the date of death found in the hospital records or social security data. DSS was calculated from the day of biopsy or definitive surgery until the last known follow-up or death from PGC reported in the patient record. Patients who died from causes other than the disease being studied are not counted in this measurement. Treatment outcome was evaluated through the occurrence of locoregional relapse of the disease or development of distant metastases. RFS was defined as the time from the date of biopsy or definitive surgery to the date of locoregional recurrence free survivalor DMFS reported in the patient record.

COVARIATES

Covariates were composed of a set of heterogeneous variables grouped into the following categories: demographic, pathologic, and clinical.

ANALYSES

Unadjusted and adjusted hazard ratios for each variable were calculated with univariate and multivariable Cox regression. The tatistical significance was defined at a P value of < .05.

RESULTS

The cohort of 112 patients included 62 males (55%) and 50 (45%) females. The mean age of the patients was 60.52 ± 15.22 years. The median follow-up time was 59 months (3-221 months). Adenoid cystic carcinoma was the most common tumor type with the incidence of 45%. Cumulative OS for the 5-and 10-year follow-up period was 75 and 61%, respectively. Locoregional recurrences occurred with 27 patients (24%), distant metastases occurred with 25 patients (22%), and both were diagnosed with 5 patients (6%). The number of metastatic nodes was the most important nodal prognostic factor related to OS (P = .02; HR = 2.67; CI = 0.03-6.35), DSS (P = .011; HR = 2.55; CI = .61-6.83), and DMFS (P = .005; HR = 2.85; CI = 0.12-4.76). The presence of pathological parotid nodes was associated with poorer RFS (P = .015; HR = 3.45; CI = 0.25-6.02).

CONCLUSION AND RELEVANCE

The number of metastatic lymph nodes, instead of ENE and largest nodal diameter, was the contributing factor associated with survival and treatment outcomes of surgically treated patients with high-grade PGC. Since the main function of staging system is to predict outcomes, the significance of ENE and nodal dimension in salivary gland cancer staging system requires further clarification. An important finding in the present study was that the presence of positive parotid lymph nodes was associated to locoregional treatment failure.

Current Developments in Diagnosis of Salivary Gland Tumors: From Structure to Artificial Intelligence

Salivary glands tumors are uncommon neoplasms with variable incidence, heterogenous histologies and unpredictable biological behaviour. Most tumors are located in the parotid gland. Benign salivary tumors represent 54-79% of cases and pleomorphic adenoma is frequently diagnosed in this group. Salivary glands malignant tumors that are more commonly diagnosed are adenoid cystic carcinomas and mucoepidermoid carcinomas. Because of their diversity and overlapping features, these tumors require complex methods of evaluation. Diagnostic procedures include imaging techniques combined with clinical examination, fine needle aspiration and histopathological investigation of the excised specimens. This narrative review describes the advances in the diagnosis methods of these unusual tumors-from histomorphology to artificial intelligence algorithms.

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.

Intraparotid node metastasis affects the long-term survival of patients with resectable recurrent parotid gland carcinoma

PURPOSE

The recurrence rate of parotid gland cancer is high, but research on the prognosis of recurrent parotid gland cancer (RPC) is relatively limited. We aim to determine the potential prognosis factors of RPC.

STUDY DESIGN

Retrospective cohort analysis.

SETTING

Tertiary cancer center.

METHODS

We conducted a retrospective review from 2012 to 2021 on RPC patients treated at the China National Cancer Center (CNCC). To analyze the impact of various variables on overall survival (OS) after recurrence, a univariate and multivariate Cox proportional hazard model was employed.

RESULTS

A total of 50/218 (23.0%) patients diagnosed with RPC and underwent surgery. The 5-year OS of all RPC patients in this cohort was 61.9%. 5 of 50 patients (10%) exhibited intraparotid node (IPN) metastasis. By univariate and multivariate analyses, we found that IPN metastasis was one of the prognostic factors of OS (p = 0.039) in RPC patients. The presence of IPN metastasis was also related to poor survival in individuals with negative cervical lymph nodes (CN0) (p = 0.011). In terms of the influence of surgical margins on prognosis, our findings revealed that RPC patients with negative margins exhibited a higher survival result than those with positive margins (p = 0.002).

CONCLUSION

According to this study, IPN metastasis indicate a high incidence of mortality in recurrent parotid cancer patients. Particularly, in CN0 patients, the presence of IPN metastasis was associated with poor survival in CN0 patients.

Histopathological Aspects of the Prognostic Factors for Salivary Gland Cancers

Salivary gland cancers (SGCs) are diagnosed using histopathological examination, which significantly contributes to their progression, including lymph node/distant metastasis or local recurrence. In the current World Health Organization (WHO) Classification of Head and Neck Tumors: Salivary Glands (5th edition), malignant and benign epithelial tumors are classified into 21 and 15 tumor types, respectively. All malignant tumors have the potential for lymph node/distant metastasis or local recurrence. In particular, mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (AdCC), salivary duct carcinoma, salivary carcinoma, not otherwise specified (NOS, formerly known as adenocarcinoma, NOS), myoepithelial carcinoma, epithelial-myoepithelial carcinoma, and carcinoma ex pleomorphic adenoma (PA) are relatively prevalent. High-grade transformation is an important aspect of tumor progression in SGCs. MEC, AdCC, salivary carcinoma, and NOS have a distinct grading system; however, a universal histological grading system for SGCs has not yet been recommended. Conversely, PA is considered benign; nonetheless, it should be cautiously treated to avoid the development of metastasizing/recurrent PA. The aim of this review is to describe the current histopathological aspects of the prognostic factors for SGCs and discuss the genes or molecules used as diagnostic tools that might have treatment target potential in the future.

Role of Intra-Parotid Lymph Node Metastasis in Primary Parotid Carcinoma

The parotid gland contains intra-glandular lymph nodes, the distribution of which is crucial for understanding the pathogenesis of intra-parotid lymph node metastases of parotid carcinoma and other head and neck carcinomas. Positive intra-parotid lymph node metastasis predicts the risk of positive cervical nodal metastasis. It is important to establish whether prophylactic neck dissection, including intra-parotid lymph nodes, contributes to treatment outcomes. The presence or absence of intra-parotid lymph nodes or metastasis-positive lymph nodes warrants further study. A preoperative diagnosis by imaging and fine-needle aspiration cytology of intra-parotid lymph nodes is difficult. Although intraoperative frozen section biopsy is performed during surgery, it is challenging to identify intra-parotid lymph nodes. The number of lymph nodes was the largest (47%) in the lower half of the superficial lobe, with 35% of nodes being concentrated in the inferior part of the cervicofacial branch, i.e., the lower pole of the parotid gland. Therefore, superficial parotidectomy and lower pole lobectomy need to be performed in cases in which a malignant tumor localizes to the superficial lobe or a lower pole. When intra-parotid lymph node metastases are detected during surgery, selective neck dissection (at least levels II and III) needs to be simultaneously performed.

Salivary gland cancer: ESMO-European Reference Network on Rare Adult Solid Cancers (EURACAN) Clinical Practice Guideline for diagnosis, treatment and follow-up

•This ESMO–EURACAN Clinical Practice Guideline provides key recommendations for managing salivary gland cancer. •The guideline covers clinical and pathological diagnosis, staging and risk assessment, treatment and follow-up. •Treatment algorithms for parotid, submandibular, sublingual and minor salivary gland cancer are provided. •The author group encompasses a multidisciplinary group of experts from different institutions and countries in Europe. •Recommendations are based on available scientific data and the authors’ collective expert opinion.

Surgical margins of the oral cavity: is 5 mm really necessary?

Background

Squamous cell carcinoma is the most common malignancy of the oral cavity. Primary treatment involves surgical resection of the tumour with a surrounding margin. Historically, the most commonly accepted margin clearance is 5 mm. This distance is controversial, with recent publications suggesting closer margins do not impact local recurrence and survival. The objective of this study is to determine the closest surgical margin that does not impact local recurrence and overall survival.

Methods

A retrospective review of the London Health Sciences Centre Head and Neck Multidisciplinary Clinic between 2010 and 2018 was performed. Demographic data, subsite, tumour staging, treatment modality, margins, and survival outcomes were analyzed. The primary endpoint was local recurrence free survival. Secondary endpoints included recurrence-free survival and overall survival. Descriptive statistics, as well as univariable and multivariable Cox proportional hazards regression modelling were performed for all patients.

Results

Four-hundred and twelve patients were included in the study, with a median follow-up of 3.3 years. On univariable analysis, positive margins and margins < 1 mm were associated with significantly worse local recurrence-free survival, recurrence-free survival, and overall survival (p < 0.05), compared to margins > 5 mm. Patients with surgical margins > 1 mm experienced similar outcomes to those with margins > 5 mm. Multivariable analysis identified age of diagnosis, alcohol consumption, pathological tumour and nodal category as predictors of local recurrence free survival.

Conclusions

Although historical margins for head and neck surgery are 5 mm, similar outcomes were observed for margins greater than 1 mm in our cohort. These findings require validation through multi-institutional collaborative efforts.

Graphical abstract

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Salivary Glands

The salivary gland section in the 5th edition of the World Health Organization Classification of Head and Neck Tumours features a description and inclusion of several new entities, including sclerosing polycystic adenoma, keratocystoma, intercalated duct adenoma, and striated duct adenoma among the benign neoplasms; and microsecretory adenocarcinoma and sclerosing microcystic adenocarcinoma as the new malignant entities. The new entry also includes mucinous adenocarcinoma subdivided into papillary, colloid, signet ring, and mixed subtypes with recurrent AKT1 E17K mutations across patterns suggesting that mucin-producing salivary adenocarcinomas represent a histologically diverse single entity that may be related to salivary intraductal papillary mucinous neoplasm (IPMN). Importantly, the number of entities in the salivary chapter has been reduced by omitting tumors or lesions if they do not occur exclusively or predominantly in salivary glands, including hemangioma, lipoma, nodular fasciitis and hematolymphoid tumors. They are now discussed in detail elsewhere in the book. Cribriform adenocarcinoma of salivary gland origin (CASG) now represents a distinctive subtype of polymorphous adenocarcinoma (PAC). PAC is defined as a clinically, histologically and molecularly heterogeneous disease group. Whether CASG is a different diagnostic category or a variant of PAC is still controversial. Poorly differentiated carcinomas and oncocytic carcinomas are discussed in the category "Salivary carcinoma not otherwise specified (NOS) and emerging entities". New defining genomic alterations have been characterized in many salivary gland tumors. In particular, they include gene fusions, which have shown to be tightly tumor-type specific, and thus valuable for use in diagnostically challenging cases. The recurrent molecular alterations were included in the definition of mucoepidermoid carcinoma, adenoid cystic carcinoma, secretory carcinoma, polymorphous adenocarcinoma, hyalinizing clear cell carcinoma, mucinous adenocarcinoma, and microsecretory adenocarcinoma.

Fine needle aspiration of salivary gland carcinomas with high-grade transformation: A multi-institutional study of 22 cases and review of the literature

BACKGROUND

High-grade transformation (HGT) is a rare process whereby conventional low- to intermediate-grade salivary gland carcinomas (SGC) transform into high-grade, poorly or undifferentiated malignancies with focal or complete loss of their conventional histomorphologic features. Because tumors with HGT are associated with a worse prognosis than their conventional counterparts, preoperative recognition of HGT may be of benefit for optimal patient management. Using a multi-institutional approach, we describe the largest fine needle aspiration (FNA) cohort of salivary gland carcinomas with HGT.

METHODS

The archives of 9 large academic medical centers were searched, and 22 cases of SGC with HGT were identified by surgical excision accompanied by preoperative FNA. Clinical and cytomorphologic features were retrospectively reviewed.

RESULTS

The male-to-female ratio was 14:8, and the mean patient age was 60.2 years. The average tumor size was 3.6 cm, and 19 cases were from the parotid gland. Acinic cell carcinoma with HGT was the most common tumor subtype, comprising 12 cases with HGT, followed by adenoid cystic carcinoma, secretory carcinoma, and other subtypes. Eighteen cases were classified as malignant; however, a specific diagnosis of HGT was not made. Sixteen cases contained a high-grade cytologic component, and 7 cases had a mixture of both conventional and high-grade components retrospectively.

CONCLUSIONS

SGC with HGT should be considered in the differential diagnosis of a salivary gland aspirate exhibiting high-grade cytomorphologic features. The presence of distinct tumor populations, conventional and high-grade, should prompt consideration of HGT, especially when the conventional component is acinic cell carcinoma or adenoid cystic carcinoma.

Prognostic role of intraparotid lymph node metastasis in primary parotid cancer: Systematic review

BACKGROUND

The prognostic importance of intraparotid lymph node metastasis (P+) in patients with primary parotid gland carcinoma is unclear.

METHODS

Nineteen retrospective and noncomparative cohort studies, published between 1992 and 2020, met the inclusion criteria and included 2202 patients for this systematic review.

RESULTS

The pooled prevalence of the P in adult patients in the unselected studies was 24.10% (95% confidence interval = 17.95-30.25). The number of P+ lymph nodes per patient was counted in only three studies and ranged from 1 to 11. The 5-year recurrence-free survival rate based on Kaplan-Meier analysis varied from 83% to 88% in P- patients compared to 36% to 54% in P+ patients. The average hazard ratio for tumor recurrence in patients with P+ compared to P- was 2.67 ± 0.58.

CONCLUSIONS

P+ is an independent negative prognostic factor in primary parotid gland cancer and should be included into the treatment planning.

Prognostic Implication of Histopathologic Indicators in Salivary Duct Carcinoma: Proposal of a Novel Histologic Risk Stratification Model

Salivary duct carcinoma (SDC) is a rare, aggressive malignancy that histologically resembles high-grade mammary duct carcinoma. Because of the rarity of this entity, data verifying the association between histologic features and patient survival are limited. We conducted a comprehensive histologic review of 151 SDC cases and performed an analysis of the association between various histomorphologic parameters and the clinical outcome with the aim of developing a histologic risk stratification model that predicts the prognosis of SDC patients. A multivariate analysis revealed that prominent nuclear pleomorphism (overall survival [OS]: P=0.013; progression-free survival [PFS]: P=0.019), ≥30 mitoses/10 HPF (PFS: P=0.013), high tumor budding (OS: P=0.011; PFS: P<0.001), and high poorly differentiated clusters (OS: P<0.001; PFS: P<0.001) were independent prognostic factors. Patients with vascular invasion demonstrated a marginally significant association with shorter PFS (P=0.064) in a multivariate analysis. We proposed a 3-tier histologic risk stratification model based on the total number of positive factors among 4 prognostically relevant parameters (prominent nuclear pleomorphism, ≥30 mitoses/10 HPF, vascular invasion, and high poorly differentiated clusters). The OS and PFS of patients with low-risk (0 to 1 point) (23% of cases), intermediate-risk (2 to 3 points) (54% of cases), and high-risk (4 points) (23% of cases) tumors progressively deteriorated in this order (hazard ratio, 2.13 and 2.28, and 4.99 and 4.50, respectively; Ptrend<0.001). Our histologic risk stratification model could effectively predict patient survival and may be a useful aid to guide clinical decision-making in relation to the management of patients with SDC.

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.

Intracapsular carcinoma ex basal cell adenoma of the parotid gland

Malignant transformation of basal cell adenoma is extremely rare. We report the case of a 63-year-old Chinese woman, who had noticed a slowing growing mass in her right parotid gland with slight pain for 1 month. Based on physical and ultrasound examinations, a diagnosis of benign salivary gland tumour was made before the surgery. A frozen biopsy was performed, and the diagnosis was basal cell adenoma, with the tumour cells infiltrating the capsule. Routine histopathological examination was performed after the surgery, and a final diagnosis of intracapsular basal cell adenocarcinoma ex basal cell adenoma was made. The patient received a further total parotidectomy and recovered well without any evidence of facial nerve palsy. This case suggests that during frozen biopsy, adequate sectioning including the capsule should be made. With regard to the treatment, we suggest a complete excision of the tumour with tumour-free margins, without any additional auxiliary therapy.