Comparative analysis of elastosonography and 18 F-FDG PET/CT in differentiating benign and malignant salivary gland tumors: a systematic review and meta-analysis

PURPOSE

We conducted a systematic review and meta-analysis to assess and compare the diagnostic performance of elastosonography and 18 F-FDG PET/CT in differentiating between benign and malignant salivary gland tumors.

METHODS

Using PICOS criteria, experimental and observational research evaluating elastosonography or 18 F-FDG PET/CT for differentiating benign and malignant salivary gland tumors were included. A systematic search was conducted across PubMed, Embase, Web of Science, Scopus, Cochrane Library, and CINAHL, initially in July 2024 and updated in February 2025. A manual search for relevant gray literature was also performed. Data extraction and risk of bias assessment using QUADAS-2 were conducted independently by reviewers.

RESULTS

A total of 26 studies with 1609 patients were included in the analysis. The pooled sensitivity of elastosonography and 18 F-FDG PET/CT in the differential diagnosis of benign and malignant salivary gland tumors were 0.75 (95% CI 0.65-0.84) and 0.84 (95% CI 0.78-0.90), specificity was 0.79 (95% CI 0.69-0.87) and 0.85 (95% CI 0.69-0.96), respectively. The area under the curve (AUC) for elastosonography and 18 F-FDG PET/CT were 0.83 and 0.92 and there is a statistical difference between the two imaging modalities (Z = 2.77, P < 0.01). Fagan nomogram indicated that when the pre-test probability was set at 20%, the post-test probability for elastosonography and 18 F-FDG PET/CT could increase to 50% and 65%.

CONCLUSION

In differentiating between benign and malignant salivary gland tumors, 18 F-FDG PET/CT exhibits a superior AUC compared to elastosonography, suggesting that, despite its current limited use in the initial workup of salivary gland tumors, there may be a strong argument for its increased adoption in clinical practice. Nevertheless, it is crucial to note that the findings of this meta-analysis rely on studies with limited sample sizes. More extensive prospective studies are warranted to validate these results further.

Lymph node surgery for salivary gland cancer: REFCOR recommendations by the formal consensus method

OBJECTIVE

To determine the indications for neck dissection in the management of parotid, submandibular or minor salivary gland cancers depending on the clinical situation: i.e., clinical lymph node involvement (cN+) or not (cN0); low or high risk of occult nodal metastasis; diagnosis of malignancy before, during or after surgery.

MATERIAL AND METHODS

The French Network of Rare Head and Neck Tumors (REFCOR) formed a steering group which 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

In cN+ salivary gland cancer, ipsilateral neck dissection is recommended. In cN0 salivary gland cancer, ipsilateral neck dissection is recommended, except for tumors at low risk of occult nodal metastasis. If definitive pathology reveals a high risk of occult nodal involvement, additional neck treatment is recommended: ipsilateral neck dissection or elective nodal irradiation.

CONCLUSION

The rate of occult lymph node involvement, and therefore the indication for elective neck dissection, depends primarily on the pathologic grade of the salivary gland cancer.

Diagnostic imaging of salivary gland cancers: REFCOR recommendations by the formal consensus method

OBJECTIVE

To define the indications for each imaging modality in the screening, characterization, extension and follow-up of salivary gland tumors.

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

If a swelling of a salivary gland is palpable for 3 weeks, an ultrasound scan is recommended to confirm a tumoral lesion and rule out differential diagnoses. For a salivary gland tumor, MRI is recommended with diffusion-weighted and dynamic contrast-enhanced techniques. In the case of histologically proven malignancy or a highly suspicious lesion, a CT scan of the neck and chest is recommended to assess the tumor, lymph nodes and metastases. FDG-PET is not currently recommended in routine clinical practice for initial diagnosis, assessment of extension, evaluation of response to treatment, staging of recurrence, or follow-up of salivary gland tumors.

CONCLUSION

Assessing salivary tumors is based on MRI. Extension assessment is based on neck and chest CT.

Major Salivary Gland Cancer With Distant Metastasis Upon Presentation: Patterns, Outcomes, and Imaging Implications

OBJECTIVES

Given limited data availability on distant metastasis (DM) in major salivary gland (MSG) malignancy presentation, we aimed to evaluate the rate, histologic patterns, location, and predictors of DM at first MSG cancer presentation and suggest potential implications on diagnostic workup.

STUDY DESIGN

Retrospective cohort.

SETTING

Commission on Cancer-accredited hospitals.

METHODS

We included patients in the National Cancer Database (2010-2016) with MSG malignancy. Site and rate of DM were stratified by histologic subtype. Factors predictive of DM at presentation were determined by multivariate regression analysis. Survival analyses were conducted via the Kaplan-Meier method, log-rank test, and Cox regression analysis.

RESULTS

Of 5776 patients with MSG carcinoma, 333 (5.8%) presented with DM. The most common DM site was the lung (57.1%), followed by bone (46.8%) and liver (19.5%). DM was most common in adenocarcinoma-not otherwise specified (15.1%, 132/874) and salivary duct carcinoma (10.4%, 30/288). High-grade mucoepidermoid carcinoma had the highest rate of lung metastases (81.6%, 31/38). Conversely, myoepithelial carcinoma had the highest rate of bone metastases (85.7%, 6/7). DM at presentation was independently associated with an increased mortality risk (hazard ratio, 1.62; 95% CI, 1.40-1.90).

CONCLUSION

We identified a DM rate of 5.8% in MSG malignancy at presentation. Overall 43% of patients presented without DM to the lung but with DM to the bones, liver, and/or brain. The most common metastatic sites differed by tumor histology. Staging with computed tomography neck and chest alone may fail to detect sites of DM; this work can be used for patient counseling in the clinical setting.

Management of malignant submandibular gland tumors: A 30-year experience from a single center

OBJECTIVE

Owing to histologic heterogeneity, biological behavior, and rarity, recommendations for the treatment of malignant submandibular gland tumors (MSGT) are inconsistent. The aim of this study was to present a single-center experience in the treatment of MSGT with an emphasis on surgical treatment, including indication on elective neck dissection (END).

STUDY DESIGN

Twenty-four MSGT were primary surgically treated (gland excision with neck dissection). Their records were retrospectively collected and analyzed.

RESULTS

The most frequent histology was adenoid cystic carcinoma (41.6%), followed by mucoepidermoid carcinoma (25%) and carcinoma ex pleomorphic adenoma (16.7%). There were 18 elective and 6 therapeutic neck dissections. Histopathologic examination confirmed 29% (7/24) of positive neck dissection specimens. The Kaplan-Meier analysis presented rates of disease-specific survival, disease-free survival, and overall survival (OS) of 81%, 78%, and 52% at 5 years, respectively. Patients undergoing postoperative radiotherapy had significantly higher OS rates compared with patients treated with surgery alone (P = .0209).

CONCLUSION

Results of this study suggest that END has questionable benefit in early stage MSGT. Elective selective neck dissection levels I-III is recommended in high-grade and advanced stage MSGT without evidence of multilevel lymphadenopathy.

18F-FDG-PET/CT interpretation pitfalls in patients with head and neck cancer

AIM

The aim of the present study is to raise awareness of ENT Surgeons on the limitations of ¹⁸F-FDG PET/CT in head and neck cancer by presenting illustrative cases from our department archives.

MATERIALS AND METHODS

A retrospective chart review was conducted for all patients with head and neck cancer treated in our ENT department from 2015 to 2020. Cases with various interpretation pitfalls due to false-positive and false-negative PET/CT results that lead to diagnostic dilemmas and treatment delays either in their pre-therapeutic work-up or in their post-therapeutic monitoring were included.

RESULTS

Five cases of various image interpretation pitfalls (3 false negative and 2 false positive cases) were identified and are presented in detail.

CONCLUSIONS

Although ¹⁸F-FDG PET/CT has gained in popularity and improved head and neck cancer management, clinicians should be aware of its limitations. The combination of ¹⁸F-FDG PET/CT with other imaging modalities can reduce the number of interpretation pitfalls but by no means will substitute sound clinical judgement.

Salivary gland carcinoma in children and adolescents: The EXPeRT/PARTNER diagnosis and treatment recommendations

Salivary gland carcinomas (SGCs) are rare during childhood and adolescence. Consequently, no standardized recommendations for the diagnosis and therapeutic management of pediatric SGC are available, and pediatric oncologists and surgeons generally follow adult guidelines. Complete surgical resection with adequate margins constitutes the cornerstone of treatment. However, the indications and modalities of adjuvant therapy remain controversial and may be challenging in view of the potential long-term toxicities in the pediatric population. This paper presents the consensus recommendations for the diagnosis and treatment of children and adolescents with SGCs, established by the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) within the EU-funded PARTNER project (Paediatric Rare Tumours Network - European Registry).

Management of Salivary Gland Malignancy: ASCO Guideline

PURPOSE

To provide evidence-based recommendations for practicing physicians and other healthcare providers on the management of salivary gland malignancy.

METHODS

ASCO convened an Expert Panel of medical oncology, surgical oncology, radiation oncology, neuroradiology, pathology, and patient advocacy experts to conduct a literature search, which included systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 2000 through 2020. Outcomes of interest included survival, diagnostic accuracy, disease recurrence, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations.

RESULTS

The literature search identified 293 relevant studies to inform the evidence base for this guideline. Six main clinical questions were addressed, which included subquestions on preoperative evaluations, surgical diagnostic and therapeutic procedures, appropriate radiotherapy techniques, the role of systemic therapy, and follow-up evaluations.

RECOMMENDATIONS

When possible, evidence-based recommendations were developed to address the diagnosis and appropriate preoperative evaluations for patients with a salivary gland malignancy, therapeutic procedures, and appropriate treatment options in various salivary gland histologies.Additional information is available at www.asco.org/head-neck-cancer-guidelines.

Pre-treatment metabolic tumor volume predicts tumor metastasis and progression in high-grade salivary gland carcinoma

PURPOSE

High-grade salivary gland carcinoma (SGC) shows a high rate of metastasis and post-treatment recurrence, resulting in poor patient survival. Therefore, we evaluated the utility of pre-treatment 18F-FDG PET/CT parameters in predicting metastasis, tumor progression, and survival of high-grade SGC patients.

METHODS

This observational study included 75 patients with previously untreated high-grade SGC who underwent pre-treatment 18F-FDG PET/CT scanning and subsequent treatment. Standardized uptake values (SUV), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured on pre-treatment 18F-FDG PET/CT. Logistic regression analysis was used to identify the relationship of these factors with metastasis. Cox proportional hazard regression analyses were used to identify associations between PET parameters and both progression-free survival (PFS) and overall survival (OS).

RESULTS

A total of 36 (48%) patients had neck or distant metastases at initial staging. After controlling for clinical factors, MTV (> 8.8 mL) was an independent factor for initial metastasis (adjusted odds ratio 4.80, 95% confidence interval 1.09-21.20; P = 0.039). All PET parameters of SUVmax (> 4.3), SUVmean (> 3.0), SUVpeak (3.9), MTV (> 8.8 mL), and TLG (> 31.1 g) were significant variables for PFS (all P < 0.05), while MTV and TLG were significant factors for OS. After controlling for clinicopathological factors, MTV (adjusted hazard ratio 4.36, 95% confidence interval 1.69-11.26; P = 0.002) and TLG (3.41, 1.47-7.91; P = 0.004) were significantly associated with PFS, but not OS.

CONCLUSIONS

MTV is useful among quantitative PET measurements for predicting initial metastasis and PFS in patients with high-grade SGC.

Contemporary Management of Benign and Malignant Parotid Tumors

To report the standard of care, interesting new findings and controversies about the treatment of parotid tumors. Relevant and actual studies were searched in PubMed and reviewed for diagnostics, treatment and outcome of both benign and malignant tumors. Prospective trials are lacking due to rarity of the disease and high variety of tumor subtypes. The establishment of reliable non-invasive diagnostics tools for the differentiation between benign and malignant tumors is desirable. Prospective studies clarifying the association between different surgical techniques for benign parotid tumors and morbidity are needed. The role of adjuvant or definitive radiotherapy in securing loco-regional control and improving survival in malignant disease is established. Prospective clinical trials addressing the role of chemotherapy/molecular targeted therapy for parotid cancer are needed. An international consensus on the classification of parotid surgery techniques would facilitate the comparison of different trials. Such efforts should lead into a clinical guideline.

Preoperative evaluation and surgical planning of submandibular gland tumors

BACKGROUND

Roughly half of submandibular gland neoplasms are malignant. Because preoperative information on the nature of these tumors remains limited, both preoperative evaluation and assessment of the extent of primary surgery warrant guidelines that are more accurate.

METHODS

We evaluated the preoperative examinations and management of all submandibular gland neoplasms treated surgically at the Helsinki University Hospital between 2000 and 2010.

RESULTS

Of the 83 tumors, 58 (70%) were benign and 25 (30%) were malignant. Of the benign tumors, 54 (93%) were pleomorphic adenomas. The cytology in 8 patients (10%) was class IV or V, and in 12 patients was class III; the tumors in 9 of these 12 patients turned out to be malignant. Of all malignancies, 10 (40%) required additional more extensive surgery.

CONCLUSION

Ultrasound-guided fine-needle aspiration cytology (FNAC) proved useful, with limitations, in preoperative examination. Surgeons should always obtain wide margins whenever possible, even when clinical means or cytology indicates no malignancy. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1071-1077, 2017.

De novo myoepithelial carcinoma with multiple metastases arising from a submandibular salivary gland: A case report

Salivary gland carcinomas are rare tumors, representing ~0.5% of all malignancies. Myoepithelioma is also uncommon, representing ~1% of all salivary gland tumors. Myoepithelial carcinoma (MC) is even rarer, representing 0.2 to 0.6% of all salivary gland tumors. We herein report a case of MC with multiple metastases arising from a submandibular gland in a 71-year-old male patient and present the associated imaging findings. The patient was considered to have a de novo type of myoepithelial carcinoma, which is reportedly associated with higher malignancy than the transformation type of the disease (i.e., a malignant change from pleomorphic adenoma or myoepithelioma). This was reflected in the multiple lung and bone metastases sites and strong positivity for p53 and Ki-67.

Extensive Regional Metastasis of High-Grade Mucoepidermoid Carcinoma of an Unknown Primary Tumor

PURPOSE

Mucoepidermoid carcinoma (MEC) is the most common salivary carcinoma. It arises most frequently in the major salivary glands, but can also arise in minor glands or intraosseous sites. MEC of an unknown primary occurs very rarely. The present report documents only the third case reported in medical studies.

METHODS

A 66-year-old man with previous carcinoma in situ (CIS) of the left posterior oral tongue that had been excised in 2004 and again in 2010 presented with a hard lymph node, 3 × 2 cm at level II of the right neck in July 2015. Positron emission tomography-computed tomography (PET-CT) revealed multiple, bilateral cervical lymphadenopathy, with no primary site identified. Fine needle aspiration biopsy and cytologic examination from the right neck was positive for malignancy, suggestive of metastatic squamous cell carcinoma. Panendoscopy and biopsy revealed CIS at the tongue bases and tonsils bilaterally (p16-negative). The patient's case was presented to a tumor board, and definitive concurrent cispl.atin-based chemoradiation was recommended for TisN2cM0, stage IVA oropharyngeal CIS, which was completed in November 2015. PET-CT in January 2015 showed complex interval changes, with some areas demonstrating improvement (ie, no uptake in the left neck) and worsening in others (ie, increased metabolic activity in the right neck), suggestive of residual disease. Repeat PET-CT in March 2016 showed increased nodal involvement and increasing standardized uptake value. Bilateral modified radical neck dissection was undertaken, and histologic examination showed high-grade MEC in 51 of 61 lymph nodes with extracapsular spread and soft tissue involvement.

RESULTS

The patient died in May 2016 at 2 months after surgery.

CONCLUSIONS

Metastatic MEC of an unknown primary is a diagnostic challenge. PET-CT might not be the most reliable diagnostic investigation to identify the primary or metastatic foci, such as was demonstrated in the present case.

The role of PET/CT in the management of patients affected by head and neck tumors: a review of the literature

The management of head and neck tumor (HNSCC) has been changing over the years, especially due to the aid of imaging techniques that help physicians to attain a correct diagnosis. These techniques represent a valuable tool to help tailor treatment and during follow-up of patients affected by malignancies. The aim of this review is to summarize the results of the most recent and relevant studies about the use of PET imaging in HNSCCs. This review is divided into six chapters: (1) The role of PET/CT in the pre-treatment phase; (2) PET/CT and radiotherapy planning; (3) PET/CT in the post-treatment setting; (4) PET/CT and SUVmax for prediction of prognosis; (5) miscellanea on the utility of PET in specific HNSCCs; (6) non-FDG PET tracers used in HNSCC. Promising results have been obtained so far. Despite the encouraging outcomes, more investigations are needed to warrant the value of this technique, especially in the pre-treatment setting.

(18)FDG-PET/CT for the detection of regional nodal metastasis in patients with head and neck cancer: a meta-analysis

We performed a meta-analysis to evaluate the role of (18)FDG-PET/CT for detection of regional nodal metastasis in patients with head and neck cancer (HNC). Studies about (18)FDG-PET/CT were systematically searched in the MEDLINE and EMBASE databases. The Stata software was used to obtain pooled estimates of sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for (18)FDG-PET/CT. We also compared the performance of (18)FDG-PET/CT with that of conventional imaging (CT, MRI, and CT/MRI) by analyzing studies that had also used conventional imaging on the same patients. 24 articles bulled all inclusion criteria (1270 patients). The pooled per-patient, per-neck-side, and per-neck-level sensitivities/specificities for (18)FDG-PET/CT were 0.91/0.87, 0.84/0.83, and 0.80/0.96, respectively. Across 13 studies (3460 neck levels) with per-neck-level data, the sensitivity and specificity of PET-CT were 0.84 and 0.96, and of conventional imaging were 0.63 and 0.96, respectively. (18)FDG-PET/CT has good diagnostic performance for the detection of regional nodal metastasis in HNC patients. Compared with conventional imaging, (18)FDG-PET/CT may have higher per-neck-level sensitivity.

Prevalence and risk of malignancy of focal incidental uptake detected by fluorine-18-fluorodeoxyglucose positron emission tomography in the parotid gland: a meta-analysis

This study aimed at performing a meta-analysis on the prevalence and risk of malignancy of focal parotid incidental uptake (FPIU) detected by hybrid fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) or (18)F-FDG PET alone. A comprehensive literature search of studies published up to July 2014 was performed. Records reporting at least 5 FPIUs were selected. Pooled prevalence and malignancy risk of FPIU were calculated including 95 % confidence intervals (95 % CI). Twelve records were selected for our meta-analysis. Pooled prevalence of FPIU detected by (18)F-FDG PET or PET/CT was 0.6 % (95 % CI 0.4-0.7 %), collecting data of 220 patients with FPIU. Overall, 181 FPIUs underwent further evaluation and 165 FPIUs were pathologically proven. Pooled risk of malignancy was 9.6 % (95 % CI 5.4-14.8 %), 10.9 % (95 % CI 5.8-17.3 %) and 20.4 % (95 % CI 12.3-30 %), considering all FPIUs detected, only those which underwent further evaluation and only those pathologically proven, respectively. Selection bias in the included studies, the heterogeneity among studies and the publication bias are limitations of our meta-analysis. Overall FPIUs are observed in about 1 % of (18)F-FDG PET or PET/CT scans and they are benign in most of the cases. Nevertheless, further evaluation is needed whenever FPIUs are detected by (18)F-FDG-PET or PET/CT to exclude malignant lesions or with possible malignant degeneration. Prospective studies are needed to confirm the findings reported by our meta-analysis.