Perineural Invasion in Parotid Gland Malignancies

Nomogram based on immune-inflammatory indicators and age-adjusted charlson comorbidity index score to predict prognosis of postoperative parotid gland carcinoma patients

BACKGROUND

Parotid gland carcinoma (PGC) is a rare malignant tumor. The purpose of this study was to investigate the role of immune-inflammatory-nutrition indicators and age-adjusted Charlson comorbidity index score (ACCI) of PGC and develop the nomogram model for predicting prognosis.

METHOD

All patients diagnosed with PGC in two tertiary hospitals, treated with surgical resection, from March 2012 to June 2018 were obtained. Potential prognostic factors were identified by univariate and multivariate Cox regression analyses. The nomogram models were established based on these identified independent prognostic factors. The performance of the developed prognostic model was estimated by related indexes and plots.

RESULT

The study population consisted of 344 patients with PGC who underwent surgical resection, 285 patients without smoking (82.8%), and 225 patients (65.4%) with mucoepidermoid carcinoma, with a median age of 50.0 years. American Joint Committee on Cancer (AJCC) stage (p < 0.001), pathology (p = 0.019), tumor location (p < 0.001), extranodal extension (ENE) (p < 0.001), systemic immune-inflammation index (SII) (p = 0.004), prognostic nutrition index (PNI) (p = 0.003), ACCI (p < 0.001), and Glasgow prognostic Score (GPS) (p = 0.001) were independent indicators for disease free survival (DFS). Additionally, the independent prognostic factors for overall survival (OS) including AJCC stage (p = 0.015), pathology (p = 0.004), tumor location (p < 0.001), perineural invasion (p = 0.009), ENE (p < 0.001), systemic immune-inflammation index (SII) (p = 0.001), PNI (p = 0.001), ACCI (p = 0.003), and GPS (p = 0.033). The nomogram models for predicting DFS and OS in PGC patients were generated based on these independent risk factors. All nomogram models show good discriminative capability with area under curves (AUCs) over 0.8 (DFS 0.802, and OS 0.825, respectively). Decision curve analysis (DCA), integrated discrimination improvement (IDI), and net reclassification index (NRI) show good clinical net benefit of the two nomograms in both training and validation cohorts. Kaplan-Meier survival analyses showed superior discrimination of DFS and OS in the new risk stratification system compared with the AJCC stage system. Finally, postoperative patients with PGC who underwent adjuvant radiotherapy had a better prognosis in the high-, and medium-risk subgroups (p < 0.05), but not for the low-risk subgroup.

CONCLUSION

The immune-inflammatory-nutrition indicators and ACCI played an important role in both DFS and OS of PGC patients. Adjuvant radiotherapy had no benefit in the low-risk subgroup for PGC patients who underwent surgical resection. The newly established nomogram models perform well and can provide an individualized prognostic reference, which may be helpful for patients and surgeons in proper follow-up strategies.

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.

Differential expression of TRKB tyrosine kinase in the two histological types of parotid salivary duct carcinoma with cancer aggressiveness

Parotid salivary duct carcinoma (SDC) is a rare and aggressive parotid gland carcinoma (PGC). SDC has two origins: de novo and ex pleomorphic adenoma (SDC ex PA); however, because of its rarity, the clinical and molecular features of the two types of SDC are not sufficiently understood. Here, we studied the differences in their clinicopathological and molecular features using clinical specimens while comparing them to those of adenoid cystic carcinoma (AdCC), an intermediate-grade PGC. Clinicopathological analysis of tissues from patients with PGC revealed significant associations between histological types and malignant phenotypes, including nodal metastasis, recurrence, vascular invasion, and neural invasion, and revealed more malignant phenotypes of de novo SDC than of SDC ex PA. The de novo SDC showed a significantly higher frequency of intra-neural invasion (intra-NI) and vascular invasion than AdCC and SDC ex PA. PGCs with high intra-NI were significantly correlated with malignant phenotypes and survival rates. Recently, we observed the overexpression of tropomyosin receptor kinase B (TRKB), a receptor tyrosine kinase, in PGC cells. Here, immunohistochemical and clinicopathological analyses showed that TRKB was highly expressed in SDC cells, particularly de novo SDC cells, and was significantly associated with poor survival and highly malignant phenotypes, including intra-NI and vascular invasion. Collectively, these data show that TRKB expression is significantly elevated in PGC, particularly in de novo SDC, and can be one of the biomarkers of their aggressiveness.

Epidemiological and histopathological patterns of malignant salivary gland tumors in the Sudanese population

Background

Malignant salivary gland tumors are rare. However, their morphological overlap and difficulty to differentiate benign from malignant makes diagnosing such diseases a challenging task. Geographical variation in distribution of these diseases is well documented in the literature. This study aims to review the histological and epidemiological variations of malignant salivary gland tumors in Sudanese patients considering the new WHO 2022 classification.

Methodology

This retrospective study included malignant salivary gland tumours in our lab spanning from the period of 2014 to 2022. Information about clinical data, habits, geographical distribution, pathological diagnosis, duration and sites of tumors were retrieved from our archives. Equivocal cases were checked by a salivary gland expert. Data analysis was performed using IBM SPSS 29.

Results

This study included 107 cases of malignant salivary gland tumours, representing 54 % of the total number of salivary gland tumours in the lab during that period. 47.7 % of the patients in this study were females and 52.3 % were males, the mean age of patients was 50 ± 15.7 years. (30 %) of the patients were from the central region of the country. The most common malignant salivary gland tumor was the Mucoepidermoid carcinoma accounting for 17 %. The palate was found to be the most common site as 38 % of malignant salivary gland tumors occurred in this site.

Conclusion

The study found a high percentage of salivary gland tumours in the Sudan suggesting geographical differentiation.

Research trends and perspectives on immediate facial reanimation in radical parotidectomy (Review)

For patients diagnosed with advanced malignant parotid tumour, radical parotidectomy with facial nerve sacrifice is part of the treatment. Multiple surgical techniques have been developed to cure facial paralysis in order to restore the function and aesthetics of the face. Despite the large number of publications over time on facial nerve reanimation, a consensus on the timing of the procedure or the donor graft selection has remained to be established. Therefore, the aim of the present study was to conduct a bibliometric analysis to identify and analyse scientific publications on the reconstruction of the facial nerve of patients who underwent radical parotidectomy with facial nerve sacrifice. The analysis on the topic was conducted using the built-in tool of the Scopus database and VOSviewer software. The first 100 most cited articles were separately reviewed to address the aim of the study. No consensus was found regarding the recommended surgical techniques for facial nerve reanimation. The most used donor cranial nerves for transfer included the following: Masseteric branch of the V nerve, contralateral VII nerve with cross-face graft, the XI nerve and the XII nerve. The best timing of surgery is also controversial depending on pre-exiting pathology and degree of nerve degeneration. However, most of the clinical experience suggests facial nerve restoration immediately after the ablative procedure to reduce complications and improve patients' quality of life.

Perineural invasion: A potential driver of cancer-induced pain

Perineural invasion (PNI) is the process through which tumors invade and interact with nerves. The dynamic changes in the nerves caused by PNI may induce disturbing symptoms. PNI-related cancer pain in neuro-rich tumors has attracted much attention because the occurrence of tumor-induced pain is closely related to the invasion of nerves in the tumor microenvironment. PNI-related pain might indicate the occurrence of PNI, guide the improvement of treatment strategies, and predict the unresectability of tumors and the necessity of palliative care. Although many studies have investigated PNI, its relationship with tumor-induced pain and its common mechanisms have not been summarized thoroughly. Therefore, in this review, we evaluated the relationship between PNI and cancer-associated pain. We showed that PNI is a major cause of cancer-related pain and that this pain can predict the occurrence of PNI. We also elucidated the cellular and molecular mechanisms of PNI-induced pain. Finally, we analyzed the possible targets for alleviating PNI-related pain or combined antitumor and pain management. Our findings might provide new perspectives for improving the treatment of patients with malignant tumors.

Facial Nerve Neurolymphomatosis That Extends to Both the Brainstem and Extracranial Regions

A 73-year-old female developed right facial paralysis of House-Brackmann (H-B) grade III and was diagnosed with Bell's palsy. After three months of steroid therapy, she developed progressive hearing loss, and an MRI revealed a tumor in the right internal auditory canal. Within a few months, the right facial nerve palsy recurred, and the patient was treated with Gamma Knife radiosurgery. The tumor in the irradiated region disappeared, but new dysphagia was observed, and a right parotid gland tumor was detected for the first time. Tumors of the right parotid gland and the digastric muscle of the jaw were surgically resected, and a diagnosis of diffuse large B-cell lymphoma was made. The tumor had invaded the cranial nerves and brainstem region, and the patient did not wish to undergo further medical therapy. This was a case of malignant lymphoma that started as facial paralysis and invaded the brainstem, and testing for possible lymphoma at an early stage prior to radiotherapy was desirable.

Salivary Ductal Carcinoma: A Case Report

ABSTRACT

Salivary ductal carcinoma is an extremely rare tumor located in the parotid gland. This case details a salivary ductal carcinoma within the parotid gland of a 59-year-old man and its management.

Immunohistochemical Expression of Epithelial Cell Adhesion Molecule (EpCAM) in Salivary Gland Cancer: Correlation with the Biological Behavior

Salivary gland neoplasms comprise a diverse group of tumors with different biological behaviors and clinical outcomes. Understanding the underlying molecular alterations associated with these malignancies is critical for accurate diagnosis, prognosis, and treatment strategies. Among the many biomarkers under investigation, epithelial cell adhesion molecule (EpCAM) has emerged as a promising candidate in salivary gland cancer research. This article aims to provide a comprehensive overview of the differential expression of EpCAM in salivary gland cancer and its potential correlation with the biological behavior of these tumors. The clinical characteristics of 65 patients with salivary gland malignancy of different histopathological subtypes were included. We report the differential expression of EpCAM and the relationship between the clinical and histopathologic features of these tumors. Regarding the evaluation of the effect of EpCAM expression on survival, in our study, we showed that tumors with high EpCAM expression had reduced disease-free survival (DFS) and overall survival (OS) (p < 0.001) compared to patients with cancers with low EpCAM expression. In addition, the concurrent presence of perineural invasion and positive EpCAM expression appeared to be associated with shorter disease-free survival and overall survival. In conclusion, our study confirmed the prognostic value of detecting perineural invasion and EpCAM expression.

Newly Discovered Parotid Lesion: What Next?

When a parotid lesion is discovered incidentally, it can be challenging for the radiologist to provide specific recommendations for the next steps. This article describes how the radiologist can play an active role in managing incidentally discovered parotid lesions. First, we explore the significance of parotid lesions. Next, the pertinent anatomy of the parotid space is presented to develop an appropriate differential diagnosis. Lastly, we discuss critical clinical and imaging characteristics the radiologist can use to provide specific recommendations.

Perineural Invasion as Worsening Criterion for Salivary Gland Mucoepidermoid Carcinoma

Mucoepidermoid carcinomas (MECs) are a form of salivary gland malignancy. They are classified according to histological grade and perineural invasion (PNI). In another cancer subtypes, positive-PNI suggests increased poor prognosis; however, the role of isolated positive-PNI salivary gland MEC can still be better investigated as a risk factor. This study investigated whether isolated PNI is independently associated with poor outcomes. Retrospective study, cohort case-series, single-center hospital from 2009 to 2019. Patient demographics, primary tumor, intervention, and survival data are included. Univariate, multivariate, and Kaplan-Meier survival curve analyses were used for comparison.The study group consisted of 32 patients (15 PNI-positive tumors, and 17 PNI-negative tumors), all admitted for surgery. Univariate analysis showed differences in grade (p = 0.038), positive margins (p = 0.034), soft tissue invasion (p < 0.001), pathological stage (p = 0.014), recurrence (p = 0.015), distant metastasis (p = 0.015) and MEC related death (p = 0.015). The risk in PNI-positive patients to develop soft tissue invasion and positive surgical margins was OR = 8.57 and OR = 4.88, respectively. Multivariate analysis found age differences (p = 0.038), with OR = 1.08. The Disease Specific Survival (DSS) was worst in the PNI-positive group (log-rank p-value = 0.0011), where the probability of dying occurred in the 12-24 months period (log-rank p-value = 0.002). PNI-positive salivary gland MEC is an independent prognostic factor, with poor DSS, increased locoregional recurrence, close correlation with a more aggressive pattern of the disease, and should be reviewed as a high grade histological criteria. Our findings may imply changes in the clinical approach with a more aggressive attitude in the overall treatment.

Intensity-modulated radiotherapy with planned Gamma Knife radiosurgery boost for head and neck cancer with extensive disease in proximity to critical structures

BACKGROUND

To describe intensity-modulated radiotherapy (IMRT) with Gamma Knife Radiosurgery (GKRS) boost for locally advanced head and neck cancer (HNC) with disease near dose-limiting structures.

METHODS

Patients with HNC treated with IMRT/GKRS as part of a combined modality approach between 2011 and 2021 were reviewed. Local control, overall survival and disease-specific survival were estimated using the Kaplan Meier method.

RESULTS

Twenty patients were included. Nineteen patients had T3-4 tumors. Median follow-up was 26.3 months. GKRS site control was 95%. Two patients progressed at the treated primary site, one patient failed at the edge of the GKRS treatment volume, with no perineural or intracranial failure. 2-year OS was 94.7% (95% CI: 85.2%-100%). Concurrent chemotherapy was given in nine patients (45%). One patient (5%) received induction/concurrent chemotherapy. Brain radionecrosis occurred in three patients, one of which was biopsy-proven.

CONCLUSIONS

IMRT plus GKRS boost results in excellent disease control near critical structures with minimal toxicity.

High-grade transformation of adenoid cystic carcinoma of parotid gland with isolated intratemporal facial nerve involvement: a case report and literature review

Background

High-grade transformation Adenoid cystic carcinoma (HGT-AdCC) of the parotid gland is a rare transformation noted in slow growing low grade AdCC. Perineural invasion and spread is an important feature of this tumor. Temporal bone involvement is rare. A total of only 10 cases of HGT-AdCC in parotid gland has been reported in literature so far predominantly in the elderly with peak incidence in 5th–6th decade.

Case presentation

We present a young lady of HGT-AdCC of right parotid gland with temporal bone involvement in the form of isolated perineural invasion (PNI) of facial nerve till the tympanic segment. She underwent right radical parotidectomy with modified radical neck dissection with modified lateral temporal bone resection and pectoralis major myocutaneous flap reconstruction. Histopathological examination revealed both low- and high-grade areas. Sections from facial nerve showed tumor invasion.

Conclusion

The radiological features of isolated perineural spread in intratympanic part of facial nerve can be easily missed if not specifically looked for. Every attempt should be made preoperatively and intraoperatively to determine the complete extent of the tumor for adequate disease clearance. A combined clinico-radiological approach aided by histopathology examination helps in early detection of this carcinoma and in better patient management.

Frozen section detected perineural spread in a grossly normal nerve away from tumor changes the surgical plan in parotid cancer

Perineural spread (PNS) through the facial nerve is a well-recognized pathway of spread in parotid cancers. Negative margins in the facial nerve are important in the total extirpation of cancer. We report a case of mucoepidermoid carcinoma of the parotid which was involving only the upper temporofacial division of the facial nerve at the periphery clinically and per-operatively. The upper trunk was divided at about 3cm away from the tumor at its junction with the lower trunk and the nerve was grossly normal. To our surprise disease was extending at this distance as a PNS in the frozen section analysis. This unexpected finding made the resection margin positive and we had to sacrifice the main trunk of the facial nerve as back as possible in the parotidectomy field for a negative margin in the nerve which was confirmed with frozen section again. The case emphasizes the importance of microscopic margin assessment of facial nerve in parotid cancers with the involvement of nerve at branches, even if imaging is negative or gross disease is not seen at the cut end or distant from the tumor-involved area.

A nomogram involving immune-inflammation index for predicting distant metastasis-free survival of major salivary gland carcinoma following postoperative radiotherapy

BACKGROUND

Postoperative radiotherapy (PORT) is beneficial in the improvement of local-regional control and overall survival (OS) for major salivary gland carcinomas (SGCs), and distant metastasis remained the main failure pattern. This study was designed to develop a nomogram model involving immune-inflammation index to predict distant metastasis-free survival (DMFS) of major SGCs.

PATIENTS AND METHODS

A total of 418 patients with major SGCs following PORT were randomly divided into a training (n = 334) and validation set (n = 84). The pre-radiotherapy neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) were calculated and transformed as continuous variables for every patient. Associations between DMFS and variables were performed by univariate and multivariable analysis using Log-rank and Cox regression methods. A nomogram was constructed based on the prognostic factors identified by the Cox hazards model. The decision curve analysis (DCA) was conducted with the training and validation set.

RESULTS

The estimated 3-, 5-, and 10-year DMFS were 79.4%, 71.8%, and 59.1%, respectively. The multivariate analysis revealed that age (p = 0.033), advanced T stage (p = 0.003), positive N stage (p < 0.001), high-risk pathology (p = 0.011), and high PLR (p = 0.001) were significantly associated with worse DMFS. The nomogram showed good calibration and discrimination in the training (AUC = 80.9) and validation set (AUC = 87.9). Furthermore, the DCA demonstrated favorable applicability, and a significant difference (p < 0.001) was observed for the DMFS between the subgroups based on the nomogram points.

CONCLUSION

The nomogram incorporating clinicopathological features and PLR presented accurate individual prediction for DMFS of the patients with major SGCs following PORT. Further external validation of the model is warranted for clinical utility.

The role of perineural invasion in parotid malignancy outcomes: A systematic review and meta-analysis

PURPOSE

At present, perineural invasion is used as a histologic indicator of aggressive salivary gland disease. In other head and neck malignancies, perineural invasion impacts staging of cancer lesions and therefore affects treatment options.

OBJECTIVE

To compare survival outcomes in primary parotid malignancies with and without perineural invasion.A systematic review pooled data from the scientific literature in patients with any primary parotid malignancy to investigate the prognosis of those with perineural invasion.

DATA SOURCES

PubMed (Medline), Scopus and Cochrane databases were queried from inception to July 2020 without any initial search constraints. Additional publications were included from review of pertinent articles.

STUDY SELECTION

Our inclusion criteria included primary parotid cancers with reported perineural invasion on survival outcomes. Exclusion criteria were non-English language text, non-human studies, reviews, textbooks, abstracts, case reports and case series. Two authors independently reviewed articles for inclusion. Of the initial 465 records, 83 articles were reviewed in full to yield a final collection of 14 studies.

DATA EXTRACTION AND SYNTHESIS

PRISMA-p guidelines were used in the reporting of our studies. A MOOSE Checklist was also used. MINORS criteria were applied to assess risk of bias. Random-effects models were used to estimate pooled effect sizes. No institutional review board review was needed for our study.

MAIN OUTCOMES AND MEASURES

Primary study outcomes were set prior to data collection and included overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS) and distant-metastasis-free survival (DMFS) in patients with and without perineural invasion.

RESULTS

Fourteen studies contributed to this meta-analysis. Compared to patients without perineural invasion, the pooled rate of mortality (HR = 3.64), time to recurrence (HR = 3.56), disease-specific mortality (HR = 2.77) and distant metastasis (HR = 3.84) was significantly higher for patients with PNI (all p <.001). Controlling for perineural invasion status, no moderator was associated with these survival outcomes (all p >.05). Given the clinical severity of perineural invasion, few studies were null as shown in a panel of publication bias plots.

CONCLUSION

Perineural invasion portends a poor survival outcome in patients with parotid malignancies.

LEVEL OF EVIDENCE: 1

Targeting tumor innervation: premises, promises, and challenges

A high intratumoral nerve density is correlated with poor survival, high metastasis, and high recurrence across multiple solid tumor types. Recent research has revealed that cancer cells release diverse neurotrophic factors and exosomes to promote tumor innervation, in addition, infiltrating nerves can also mediate multiple tumor biological processes via exosomes and neurotransmitters. In this review, through seminal studies establishing tumor innervation, we discuss the communication between peripheral nerves and tumor cells in the tumor microenvironment (TME), and revealed the nerve-tumor regulation mechanisms on oncogenic process, angiogenesis, lymphangiogenesis, and immunity. Finally, we discussed the promising directions of ‘old drugs newly used’ to target TME communication and clarified a new line to prevent tumor malignant capacity.

Preoperative Magnetic Resonance Image and Computerized Tomography Findings Predictive of Facial Nerve Invasion in Patients with Parotid Cancer without Preoperative Facial Weakness-A Retrospective Observational Study

Simple Summary

Facial nerve invasion in parotid cancer affects survival outcomes as well as functional outcomes after surgery-based treatment. Normal facial muscle function before surgery does not always exclude the possibility of involvement of the facial nerve by a tumor. Especially in patients without facial palsy, accurate evaluation of invasion before surgery is necessary to plan optimal facial nerve resection and reconstruction. Various findings are obtained from preoperative radiological findings, such as CT and MRI. We evaluated the role of these radiological findings in predicting nerve invasion. Large tumor, spiculated margin, and anterolateral location may suggest a high risk of nerve involvement even in patients with normal preoperative facial function. These findings may help surgeons to avoid unexpected facial nerve invasion and to make adequate surgical plans to get optimal oncological and functional outcomes.

Abstract

(1) Background: Facial nerve resection with reconstruction helps achieve optimal outcomes in the treatment of facial nerve invasion (FNI) of parotid cancer. Preoperative imaging is crucial to predict facial nerve reconstruction. The radiological findings of CT or MRI may predict FNI in the parotid cancer even without facial paralysis. Methods: We retrospectively reviewed the records of 151 patients without facial nerve paralysis before surgery who had undergone tumor resection. Previously untreated parotid cancers were included. (2) Results: The median follow-up duration was 62 months (range: 24–120 months). The FNI (+) group (n = 30) showed a significantly worse 5-year overall survival compared with the FNI (−) group (75.5 vs. 93.9%; hazard ratio = 4.19; 95% confidence interval: 1.74–10.08; p = 0.001). The tumor margin, tumor size, presence in the anterolateral parotid region (area 3), retromandibular vein involvement, distance from the stylomastoid foramen to the upper tumor margin, and a high tumor grade were significant factors related to FNI in the univariate analysis. A spiculated tumor margin, the tumor size (2.2 cm), and presence in area 3 were factors predicting FNI in the logistic regression model (p = 0.020, 0.005, and 0.050, respectively; odds ratio: 4.02, 6.40, and 8.16, respectively). (3) Conclusions: The tumor size (≥2.2 cm), spiculated margin, and presence in area 3 as presented in CT and MRI may help clinicians preoperatively predict FNI in patients with parotid cancer and establish an appropriate surgical plan.

Radiation Therapy for Adenoid Cystic Carcinoma of the Head and Neck

Simple Summary

Adenoid cystic carcinoma is a rare histology arising in the head and neck region that has a high propensity for perineural invasion. While surgical resection is the preferred primary treatment modality, adjuvant radiotherapy is often indicated to improve local control. For unresectable disease, definitive radiotherapy can be utilized. Given the predilection for perineural tumor spread, target volumes often must encompass relevant nerve pathways back to the base of skull. Treatment strategies for ACC must therefore balance the disease burden and risk of failure against the morbidity of treatment.

Abstract

Adenoid cystic carcinoma of the head and neck is an uncommon malignancy that can arise in the major or minor salivary glands. Perineural invasion (PNI) is an extremely frequent finding in cases of adenoid cystic carcinoma (ACC) that can be associated with significant patient morbidity and poor prognosis. By contrast, ACC rarely demonstrates lymphovascular space invasion thereby making PNI the major avenue for metastasis and a driver of treatment rationale and design. Radiotherapy is often utilized post-operatively to improve locoregional control or as a primary therapy in unresectable disease. Here we aim to review the role of radiotherapy in the management of this malignancy with a focus on target delineation and treatment regimens in the definitive, recurrent, and metastatic settings.

Mucoepidermoid carcinoma: Evaluating the prognostic impact of primary tumor site

Mucoepidermoid carcinoma (MEC) is one of the most common salivary gland malignancies. Our aim was to evaluate the prognostic impact of primary tumor site in patients with MEC.

MATERIAL AND METHODS

This cohort identified 308 patients with MEC who underwent primary surgery between 1985 and 2015. Survival outcomes were determined using the Kaplan-Meier method. Hazard ratios for primary site were determined using the Cox proportional-hazards model.

RESULTS

One hundred eighty (58%) patients were diagnosed with minor and 128 (42%) with major salivary gland cancer. Primary site in the minor salivary gland group included 137 (44%) oral cavity, 38 (12%) pharynx, 3 (0.9%) nasal cavity, and 2 (0.6%) trachea and larynx. The major salivary gland group included 118 (38%) parotid, 8 (3%) submandibular, and 2 (0.6%) sublingual. With a median follow-up of 73 months, 5-year overall survival and disease-specific survival were 84% and 91%, respectively. Patients with tumors located in the hard palate and retromolar trigone had the best survival, while patients with tumors located in the paranasal sinuses and submandibular gland had the poorest survival. After controlling for tumor grade and stage, MEC primary site was not predictive of survival or recurrence. On multivariate analysis, worse DSS was associated with stage III-IV tumors (HR: 7,11; 95% CI: 1.19-26.43; p = 0.0034) and high-grade tumors (HR: 19.12; 95% CI: 2.26-162.77; p = 0.0068).

CONCLUSIONS

While high grade and advanced overall stage were found to be independent predictors of worse survival, primary tumor site was not predictive of poor outcome.

Patterns of Perineural Skull Base Tumor Extension from Extracranial Tumors

Perineural extension is an increasingly recognized pathway of extension of cutaneous, mucosal, and salivary gland neoplasms associated with a severe adverse prognosis. Imaging identification is feasible by MR imaging 3-dimensional contrast-enhanced submillimetric sequences. The trigeminal nerve branches and facial nerve are the most commonly involved. PET with computed tomography may aid in the identification of the primary tumor location or recognition of recurrence, but only in conjunction with MR imaging does it achieve similar detection rates for perineural extension. Computed tomography scanning is an adjunct to MR imaging to increase specificity and for surgical treatment planning.

Predicting cancer-specific mortality in patients with parotid gland carcinoma by competing risk nomogram

BACKGROUND

The aim of the present study was to establish a competing risk nomogram to predict parotid gland cancer-specific mortality (PGC-SM).

METHODS

Seven thousand nine hundred and sixty-two patients extracted from SEER database were randomly categorized into training and validation sets. The competing risk model was used to identify factors associated with PGC-SM. The nomogram was evaluated via concordance indexes (C-indexes), calibration plots, and decision curve analysis (DCA).

RESULTS

Male, elderly, white, widowed, larger tumor, no surgery, advanced tumor grade, lymph node (LN) metastasis, adenocarcinoma (ADC), and higher TNM stage were associated with higher incidence of PGC-SM. Calibration plots showed that the nomogram was well calibrated. C-indexes for nomogram were 0.84 (95% CI: 0.81-0.86) and 0.84 (95% CI: 0.82-0.86) in training and validation sets, respectively. DCA demonstrated the clinical usefulness of nomogram.

CONCLUSIONS

The competing risk nomogram shows high performance in predicting PGC-SM, which might enable clinicians formulate suitable treatment protocols for patients with parotid gland carcinoma (PGC).

Rethinking the Definition of High Risk in Pediatric Salivary Gland Carcinoma

OBJECTIVE

Indications for adjuvant radiation in pediatric salivary gland carcinoma rely on high-risk criteria extrapolated from adult data. We sought to determine whether adult-derived high-risk criteria were prognostic in children aged ≤21 years or young adults aged 22 to 39 years.

STUDY DESIGN

Cross-sectional analysis of a hospital-based national registry.

SETTING

Patients were identified from the National Cancer Database between 2004 and 2015.

METHODS

High-risk criteria were defined as adenoid cystic histology, intermediate/high grade, T3/T4, positive margins, and/or lymph node involvement. Exact matching was used to adjust for differences in baseline characteristics between pediatric and young adult patients.

RESULTS

We identified 215 pediatric patients aged ≤21 years, 317 patients aged 22 to 30 years, and 466 patients aged 31 to 39 years. Within the pediatric cohort, there was no significant difference in overall survival (OS) between low- and high-risk groups (5-year OS, 100% vs 98.5%; P = .29). In contrast, within the young adult cohorts, there was a significant difference in OS between low- and high-risk groups in patients aged 22 to 30 years (5-year OS, 100% vs 96.1%; P = .01) and 31 to 39 years (5-year OS, 100% vs 88.5%; P < .001). When high-risk patients were matched 1:1 on high-risk criteria and race, pediatric patients were associated with better OS than those aged 22 to 30 years (P = .044) and those aged 31 to 39 years (P = .005).

CONCLUSION

Children have excellent OS, irrespective of adult-derived high-risk status. These findings underscore the need to understand how age modifies clinicopathologic risk factors.

The application of venous nerve conduit trap in the immediate repair and reconstruction of facial nerve in parotid gland tumor: an attempt of a new technique

OBJECTIVE

To introduce the application of venous nerve conduit in the immediate repair and reconstruction of facial nerve in parotid gland tumor.

METHODS

Three patients with parotid gland tumor in Sichuan Provincial Cancer Hospital were reviewed. All patients were found that the tumor encased and invaded the facial nerve which was difficult to be separated during the operation when all patients were treated with facial nerve repair and reconstruction with the venous nerve conduit trapping technique.

RESULTS

After 1-year follow-up, all patients recovered well in facial nerve function.

CONCLUSION

The venous nerve conduit trapping technique is an effective attempt in the immediate repair and reconstruction of facial nerve in parotid gland tumor, but it needs to be further confirmed by multiple studies.

Cancer-Associated Neurogenesis and Nerve-Cancer Cross-talk

In this review, we highlight recent discoveries regarding mechanisms contributing to nerve-cancer cross-talk and the effects of nerve-cancer cross-talk on tumor progression and dissemination. High intratumoral nerve density correlates with poor prognosis and high recurrence across multiple solid tumor types. Recent research has shown that cancer cells express neurotrophic markers such as nerve growth factor, brain-derived neurotrophic factor, and glial cell-derived neurotrophic factor and release axon-guidance molecules such as ephrin B1 to promote axonogenesis. Tumor cells recruit new neural progenitors to the tumor milieu and facilitate their maturation into adrenergic infiltrating nerves. Tumors also rewire established nerves to adrenergic phenotypes via exosome-induced neural reprogramming by p53-deficient tumors. In turn, infiltrating sympathetic nerves facilitate cancer progression. Intratumoral adrenergic nerves release noradrenaline to stimulate angiogenesis via VEGF signaling and enhance the rate of tumor growth. Intratumoral parasympathetic nerves may have a dichotomous role in cancer progression and may induce Wnt-β-catenin signals that expand cancer stem cells. Importantly, infiltrating nerves not only influence the tumor cells themselves but also impact other cells of the tumor stroma. This leads to enhanced sympathetic signaling and glucocorticoid production, which influences neutrophil and macrophage differentiation, lymphocyte phenotype, and potentially lymphocyte function. Although much remains unexplored within this field, fundamental discoveries underscore the importance of nerve-cancer cross-talk to tumor progression and may provide the foundation for developing effective targets for the inhibition of tumor-induced neurogenesis and tumor progression.

Nerves in the Tumor Microenvironment: Origin and Effects

Studies have reported the vital role of nerves in tumorigenesis and cancer progression. Nerves infiltrate the tumor microenvironment thereby enhancing cancer growth and metastasis. Perineural invasion, a process by which cancer cells invade the surrounding nerves, provides an alternative route for metastasis and generation of tumor-related pain. Moreover, central and sympathetic nervous system dysfunctions and psychological stress-induced hormone network disorders may influence the malignant progression of cancer through multiple mechanisms. This reciprocal interaction between nerves and cancer cells provides novel insights into the cellular and molecular bases of tumorigenesis. In addition, they point to the potential utility of anti-neurogenic therapies. This review describes the evolving cross-talk between nerves and cancer cells, thus uncovers potential therapeutic targets for cancer.

Prognostic Significance of Pain in Parotid Gland Malignancy

OBJECTIVES/HYPOTHESIS

To better understand the significance of pain as a predictor of disease severity in parotid gland malignancy.

STUDY DESIGN

A retrospective chart review of patients treated for primary parotid gland malignancy at our institution between 1991 and 2020 was performed.

METHODS

Patient records were retrospectively reviewed and relevant clinical parameters were collected. Patients were stratified into low stage (I and II) disease and high stage (III and IV) disease groups to analyze the independent effect of pain at initial presentation on disease recurrence rate and disease-free survival using Kaplan-Meier survival curves and an independent two-sample t-test.

RESULTS

Of 154 patients evaluated, there were 69 patients in the low stage group and 80 patients in the high stage group. Thirty-seven high stage patients presented with pain. High stage patients with pain were significantly more likely to develop disease recurrence than high stage patients without pain (58.5% [22/37] versus 33.3% [13/39], P = .022). High stage patients with pain also had significantly decreased disease-free survival time compared to high stage patients without pain (P = .027).

CONCLUSION

Pain on presentation appears to be a poor prognostic factor for patients with parotid gland malignancy. For patients with demonstrated high stage disease, pain is independently associated with increased risk of recurrence and decreased disease-free survival time.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1503-1508, 2021.

Acinic cell carcinoma of the salivary gland in the adult and paediatric population: a survival analysis

BACKGROUND

Acinic cell carcinoma (AcCC) is a rare malignant neoplasm of the salivary glands and generally considered to be a low-grade tumour. Surgical treatment is often curative, but a more aggressive high-grade variant has been associated with poorer survival and propensity for distant metastasis. No standard treatment guidelines exist and the approach to treatment is varied in the published series. The aim of this study is to present the experience of three major hospitals in Sydney, Australia, in treating AcCC of the salivary gland, with a focus on clinico-pathological features of disease and their associations with survival outcomes.

METHODS

Adult and paediatric cases of AcCC of the salivary gland during the time period 1979-2018 were retrospectively included. Demographic, clinico-pathological, treatment and survival outcome data were extracted. Survival analysis was undertaken to assess the effect of clinical and pathological variables on overall and disease-free survival.

RESULTS

Thirty-two cases were reviewed (29 adult and three paediatric). Thirty tumours (93.8%) were parotid gland primary tumours. Mean overall and disease-free survival was 17.0 ± 0.7 and 16.0 ± 0.9 years, respectively. Features associated with poorer survival were cT staging >1, presence of preoperative clinical facial nerve deficit and local recurrence. Positive margins were associated with recurrence.

CONCLUSION

These data suggest that disease-free and overall survival in AcCC of the salivary gland is excellent with surgery as the first-line treatment. Poor survival outcomes are uncommon and may be associated with locally advanced disease in the presence of other well-established high-risk features.

Oncological outcomes of preoperatively unexpected malignant tumors of the parotid gland

PURPOSE

Unexpected parotid cancers are often encountered due to inaccuracies in the preoperative evaluation. This study aimed to examine the clinical characteristics and oncological outcomes of these cancers and to propose the appropriate management strategy.

METHODS

This is a multicenter case series study in which a total of 302 patients were diagnosed postoperatively with parotid cancers between 2003 and 2017. Of these, 85 cases without evidence of malignancy prior to surgery but identified as malignant on postoperative pathology were included.

RESULTS

Of 85 patients, 76 and 9 underwent superficial and total parotidectomy, respectively. A positive resection margin was present in 24.7% of the cases. Postoperative radiotherapy was administered to 43.6% of patients; 4.2% had a local recurrence, and no patients died of the disease. The 5-year overall and relapse-free survival rates were 100.0% and 95.2%, respectively. Patients who underwent piecemeal resection had significantly poorer oncologic outcomes. Age, sex, histologic grade, T stage, extracapsular extension, resection margin status, and postoperative radiotherapy did not affect recurrence and survival.

CONCLUSION

Preoperatively unexpected parotid cancers had excellent local control and overall survival despite positive or close resection margin, with or without postoperative radiotherapy. Therefore, patients with unexpected parotid malignancies may benefit from less aggressive postoperative management option.

Primary squamous cell carcinoma of the parotid gland: clinicopathological characteristics, treatment, and prognosis

Squamous cell carcinoma (SCC) of the parotid gland is a rare aggressive malignancy with a poor prognosis. The clinical behaviour, histopathological characteristics, and treatment strategies for parotid SCC still need to be comprehensively demonstrated. In this study, a retrospective review of patients diagnosed with parotid SCC was performed, covering the past two decades. Twenty-nine patients with primary parotid SCC and 10 patients with recurrent parotid SCC were identified. The clinicopathological characteristics of parotid SCC were summarized. Imaging records were used to determine the extent of invasion of the parotid SCC. Histopathological alterations in the parotid resulting from the infiltration of SCC were demonstrated. A set of treatment strategies was developed, involving parotidectomy, neck dissection, facial nerve treatment, defect repair, adjuvant radiotherapy, and chemotherapy/targeted therapy. The median patient survival was 24 months for those with primary parotid SCC and 14.5 months for those with recurrent parotid SCC. Comparatively, patients with a larger tumour size of primary parotid SCC experienced poorer overall survival (hazard ratio 8.986; P=0.013). Great efforts have been made over the past two decades to identify and treat parotid SCC. Consensus regarding therapeutic options for parotid SCC has not been widely achieved and there is still a great need for well-designed prospective studies.

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.

Acinic cell carcinoma of the parotid gland: from pathogenesis to management: a literature review

PURPOSE

Acinic cell carcinoma (ACCs) is uncommon malignant epithelial neoplasm of the salivary glands; the most common presentation is a well-defined painless solid mass. Diagnosis of ACCs is frequently complicated, due to its similarity with benign tumors.

METHODS

A review of the literature available on ACCs was carried out. Studies were sourced from PubMed with searching of relevant headings and sub-headings and cross-referencing.

RESULTS

There are no clear characteristics of ACCs found on CT, MRI and ultrasound imaging. The management of the ACC, a rare malignancy of the parotid gland, is often difficult and controversial. Radical surgery is the best treatment option. The role of radiotherapy remains controversial: the precise indications and oncologic effects of adjuvant radiotherapy in ACC of the parotid gland are not well known. There is insufficient literature regarding the chemotherapy for metastatic ACC.

CONCLUSION

Knowledge about ACC, a rare malignancy of parotid gland, has changed over the past few decades. More clinical randomized works would be needed, both to assess the real effectiveness of radio and chemotherapy and to have an unanimous consensus about their indications.

Schwann Cell-Derived CCL2 Promotes the Perineural Invasion of Cervical Cancer

Perineural invasion (PNI) has guiding significances for nerve preservation in cervical cancer, but there is no definite marker indicating PNI. Two cervical cancer cell lines (HeLa and ME-180) showed significant abilities to migrate along neurites in vitro and in vivo. Morphological observation revealed that Schwann cells (SC) arrived at the sites of cervical cancer cells before the onset of cancer metastasis. We used high-throughput antibody array to screen the signals mediating the interaction of nerve cells and cancer cells and found the high expression of CCL2 in dorsal root ganglion (DRG). Meanwhile, serum CCL2 showed a notable raise especially in cervical adenocarcinoma. SC-derived CCL2 bound to its receptor CCR2 and promoted the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of cervical cancer cells. In turn, cancer cell-derived signals triggered the expression of metalloproteinases (MMPs) including MMP2, MMP9, and MMP12 in SCs, promoting SCs to dissolve matrix. These data demonstrated that the cancer-nerve crosstalk formed a tumor microenvironment (TME) that facilitated to PNI. We identified the CCL2/CCR2 axis as a potential marker to predict the PNI and affect the nerve preservation for cervical cancer.

Nomograms predictive for oncological outcomes in malignant parotid tumours: recurrence and mortality rates of 228 patients from a single institution

PURPOSE

Malignant parotid tumours are rare and multiple prognostic factors exist.

METHODS

Through a retrospective study we aimed to identify nomograms predicting recurrence and mortality rates in 228 primary parotid cancers. Patients clinical, treatment and tumour characteristics were retrospectively collected between 1980 and 2005 at our Institution. Factors predictive of disease-free-specific-survival (DSS) and overall survival (OS) were calculated by univariate and multivariate analysis. Nomograms were then constructed.

RESULTS

The 5- and 10-year DSS rates were 73% and 71.4%, and nomogram was drawn based on five parameters where perineural invasion showed the most significant predicting influence (p < 0.001). The median follow-up was of 95 months and the 5- and 10-year OS rates were 68.7% and 53.1%; six predictive variables (age, histological grade, perineural invasion, pathological lymph node status, resection margins and distant metastasis) were used to create nomogram.

CONCLUSIONS

Our nomograms provide a tailored outcome to a patient affected by malignant parotid tumour and give him/her a risk assessment for recurrence and mortality based on individual factors by a concordance index > 0.8.

Mortality rates and prognostic factors in patients with malignant salivary tumors

Malignancies of the salivary glands represent a multifarious disease. Evaluating the prognostic factors of these malignancies may help predict patient outcome and aid decision-making in choosing the most suitable therapy. We examined the role of various salivary tumorigenic, clinical and therapeutic features in a cohort of 101 patients diagnosed and treated for primary malignant salivary tumors. These include histo-pathological diagnosis, stage, grade and T, N, M values as well as the existence of perineural invasion and extra-parenchymal spread. We also identified the salivary gland involved, the sub-compartment specific location of the tumor and the therapy administered. All these were related to mortality. Of the 101 patients examined, 79 survived and 22 died due to the disease. Tumor staging, distant metastasis and perineural invasion were highly significant predictors of increased lethality. Histo-pathological grading was also a predictor but to a lesser degree. Neither neck metastasis nor tumor size or type had a significant impact on lethality. Performing neck dissections did not decrease lethality rate. Location of the tumor in the parotid gland and more so in its deep lobe adversely affected lethality; extra-parenchymal spread also had an adverse effect. Our results seem to indicate hematogenous rather than lymphogenous spread of metastasis from malignant salivary tumors. The highest therapeutic priority should be achieving full local control of the disease by safe removal of the primary salivary tumor, accompanied by regional control of perineural invasion and extra-parenchymal spread and appropriate systemic treatment aimed at eradicating distant metastasis.

Perineural invasion of cancer: a complex crosstalk between cells and molecules in the perineural niche

Perineural invasion (PNI) can be found in a variety of malignant tumors. It is a sign of tumor metastasis and invasion and portends the poor prognosis of patients. The pathological description and clinical significance of PNI are clearly understood, but exploration of the underlying molecular mechanism is ongoing. It was previously thought that the low-resistance channel in the anatomic region led to the occurrence of PNI. However, with rapid development of precision medicine and molecular biology, we have gradually realized that the occurrence of PNI is not the result of a single factor. The latest study suggests that PNI of cancer is a continuous and multistep process. A specific peripheral microenvironment, also called the perineural niche, is formed by neural cells, supporting cells, recruited inflammatory cells, altered extracellular matrix, blood vessels, and immune components in the background of carcinoma. Various soluble signaling molecules and their receptors comprise a complex signal network, which achieves the interaction between nerve and tumor. Nerve cells and tumor cells can interact directly or through the opening and closing of the signal transduction pathways and/or the recognition and response of the ligands and receptors. The information is transferred to the targets accurately and effectively, leading to the specific interactions between the nerve cells and the malignant tumor cells. PNI occurs through changes in nerve cells and supporting cells in the background of cancer; change and migration of the perineural matrix; enhancement of the viability, mobility, and invasiveness of the tumor cells; injury and regeneration of nerve cells; interaction, chemotactic movement, contact, and adherence of the nerve cells and the tumor cells; escape from autophagy, apoptosis, and immunological surveillance of tumor cells; and so on. Certainly, exploring the mechanism of PNI clearly has great significance for blocking tumor progression and improving patient survival. The current review aims to elucidate the cellular and molecular mechanisms of PNI, which may help us find a strategy for improving the prognosis of malignant tumors.

Salivary gland stem cells: A review of development, regeneration and cancer

Salivary glands are responsible for maintaining the health of the oral cavity and are routinely damaged by therapeutic radiation for head and neck cancer as well as by autoimmune diseases such as Sjögren's syndrome. Regenerative approaches based on the reactivation of endogenous stem cells or the transplant of exogenous stem cells hold substantial promise in restoring the structure and function of these organs to improve patient quality of life. However, these approaches have been hampered by a lack of knowledge on the identity of salivary stem cell populations and their regulators. In this review we discuss our current knowledge on salivary stem cells and their regulators during organ development, homeostasis and regeneration. As increasing evidence in other systems suggests that progenitor cells may be a source of cancer, we also review whether these same salivary stem cells may also be cancer initiating cells.