Cervical Lymph Node Metastasis in Adenoid Cystic Carcinoma of the Larynx: A Collective International Review

Adenoid Cystic carcinoma of minor salivary glands (AdCCmSG): a multidisciplinary update

INTRODUCTION

Adenoid cystic carcinoma of minor salivary glands (AdCCmSG) represents a 'rarity in the rarity,' posing a clinical challenge in lack of standardized, evidence-based recommendations. At present, AdCCmSG management is mostly translated from major salivary gland cancers (MSGCs). Ideally, AdCCmSG diagnostic-therapeutic workup should be discussed and carried out within a multidisciplinary, high-expertise setting, including pathologists, surgeons, radiation oncologists and medical oncologists.

AREAS COVERED

The present review provides an overview of epidemiology and pathologic classification. Moreover, the most recent, clinically relevant updates in the treatment of AdCCmSG (Pubmed searches, specific guidelines) are critically discussed, aiming to a better understanding of this rare pathologic entity, potentially optimizing the care process, and offering a starting point for reflection on future therapeutic developments.

EXPERT OPINION

The management of rare cancers is often hindered by limited data and clinical trials, lack of evidence-based guidelines, and hardly represented disease heterogeneity, which cannot be successfully tackled with a 'one-size-fits-all' approach. Our goal is to address these potential pitfalls, providing an easy-to-use, updated, multidisciplinary collection of expert opinions concerning AdCCmSG management as of today's clinical practice. We will also cover the most promising future perspectives, based on the potential therapeutic targets highlighted within AdCCmSG's molecular background.

Occult Neck Metastases in Head and Neck Adenoid Cystic Carcinoma: A Systematic Review and Meta-Analysis

Introduction: Adenoid cystic carcinoma (AdCC) is a rare tumor whose clinical course is burdened by local recurrence and distant dissemination. Lymph node metastasis is not believed to be common and its clinical impact is controversial. The aim of this study was to determine: (1) the prevalence of occult metastasis at diagnosis in cN0 head and neck AdCC, (2) its prognostic role, and (3) the consequent need to perform elective neck dissection (END). Material and Methods: A systematic review and meta-analyses following PRISMA guidelines was performed. PubMed, Embase, and Central databases were questioned up to July 2021 to identify studies reporting on the prevalence of occult neck metastases in head and neck AdCC. A single-arm meta-analysis was then performed to determine the pooled prevalence of occult lymph node metastases among the retained studies. Results: Of the initial 6317 studies identified, 16 fulfilled the inclusion criteria, and they were included in the meta-analysis. Of a population of 7534 patients, 2530 cN0 patients were treated with END, which revealed 290/2530 cases of occult metastases (pN+/cN0). Meta-analysis of the results of END in the 16 studies estimated an overall prevalence of occult metastases at diagnosis of 17%. No further subgroup analysis was possible to identify factors influencing lymph node involvement and the prognostic role of END. Conclusions: Taking 20% as an historically proposed cut off, a 17% prevalence of occult metastases represents a borderline percentage to get a definitive conclusion about the indication to END for head and neck AdCC. A more advanced UICC stage, an oropharyngeal minor salivary glands origin, and a high-grade transformation are factors to be considered in a comprehensive patient’s tailored therapeutic strategy. Multicenter prospective studies are the key to finding stronger recommendations on this topic.

Laryngeal adenoid cystic carcinoma: Radical or conservative surgery?

PURPOSE

The present paper describes our experience in surgical treatment of laryngeal ACC, and discuss the effectiveness of conservative surgery.

METHODS

We retrospectively reviewed the clinical charts of 17 patients with laryngeal ACC treated surgically at the Otolaryngology Unit of Vittorio Veneto Hospital (Italy) from November 1989 to April 2020.

RESULTS

Fourteen patients underwent partial laryngectomy, and three had a total laryngectomy. Five patients (29%) experienced a laryngeal ACC relapse after a disease-free survival of 66.6 ± 50.1 months. The distant metastasis rate was 17%. At latest follow-up, two patients had died of distant metastatic disease after 156 and 243 months.

CONCLUSIONS

Radical surgery for laryngeal ACC does not warrant free margins and even cases with positive deep margins rarely experience any relapsing disease. We recommend that surgical treatment for laryngeal ACC be as conservative as possible.

Should a neck dissection be performed on patients with cN0 adenoid cystic carcinoma? A REFCOR propensity score matching study

BACKGROUND

Patterns of nodal involvement in adenoid cystic carcinoma (ACC) of the head and neck have not been sufficiently assessed to guide a decision of prophylactic neck dissection (ND). The objective of this study is to analyse the influence of ND on event-free survival (EFS) for patients with cN0 ACC.

PATIENTS AND METHODS

A multicentre prospective study was conducted between 2009 and 2018. Patients presenting cN0 non-metastatic ACC on any site, and who received surgery on the tumour, were included. EFS was the main judgement criterion. A comparative survival analysis between the groups that received a ND versus those that did not was performed, using a propensity score. Analyses were carried out using the R software.

RESULTS

Between 2009 and 2018, 322 patients with cN0 ACC were included, out of which 58% were female. The average age was 53 years. Tumours were in minor salivary glands in 58% of cases, and 52% had T3/T4 stages. ND was performed on 46% of patients. Out of them, seven had histological lymph node invasion, out of which six had tumour infiltration in the mucosa of oral cavity. After propensity score, the median EFS for N0 patients with ND was 72 months (95% Confidence Interval (CI) [48-81]), compared to 73 months (95% CI [52-85]) for patients without ND (HR = 1.33; 95% CI [0.82-2.16]; p = 0.2).

CONCLUSION

ND of cN0 patients does not provide any benefit on EFS, which suggests that its application on such patients is not necessary.

The role of elective neck dissection in patients with adenoid cystic carcinoma of the head and neck

OBJECTIVE

To investigate the frequency and outcomes of elective neck dissection (END) for adenoid cystic carcinoma (ACC) of the head and neck.

METHODS

The National Cancer Database was queried for a cohort study of patients with ACC of the major salivary glands, nasal cavity/nasopharynx, hard/soft palate, tongue, floor of mouth, larynx, and oral cavity who underwent primary surgical resection from 2004 to 2014. Multivariable logistic regression was used to identify predictors of END and occult nodal metastasis. Overall survival (OS) was estimated using the Kaplan-Meier method and modeled with Cox proportional hazards regression.

RESULTS

Among 2,807 patients with ACC treated surgically, 636 (22.7%) underwent END. Patients with ACC of the salivary glands and tongue most frequently underwent END; patients with hard/soft palate (odds ratio [OR] 0.06, P < 0.001) and nasal cavity/nasopharynx (OR 0.05, P < 0.001) ACC rarely underwent END compared to patients with major salivary gland cancer. Increasing tumor (T) stage (T4 vs. T1, OR 3.02, P < 0.001) was associated with END. Patients with advanced T3 to T4 ACC of the major salivary glands demonstrated extended OS associated with END (5-year OS 78.1% vs. 70.4%, P = 0.041) on Kaplan-Meier analysis and with END with adjuvant radiation therapy (hazard ratio 0.55, P = 0.027) using Cox proportional hazards regression. Elective neck dissection for T4 ACC of the salivary glands (21.3%) and tongue (25.5%) most consistently revealed occult nodal metastasis.

CONCLUSION

Elective neck dissection for ACC of the major salivary glands or tongue is most likely to reveal occult nodal metastasis. Elective neck dissection is associated with extended OS for advanced-stage ACC of the major salivary glands.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:2094-2104, 2019.

Oropharyngeal adenoid cystic carcinoma invading the mandibular bone through the mandibular foramen

Adenoid cystic carcinoma (ACC) is a rare epithelial tumor of the head and neck region, and one of the most common malignant tumors of the salivary glands. ACC is a slow-growing tumor characterized by perineural invasion and often has a high-recurrence rate. We describe a case of oropharyngeal ACC invading the mandibular bone through the mandibular foramen that showed a rare pattern of origin and invasion. A 70-year-old woman complained of noise and pain around the right temporomandibular joint. Osteomyelitis was suspected on the initial imaging examinations, although the findings were slightly atypical. However, a mass was observed in the right oropharyngeal wall on subsequent imaging examinations, and mandibular bone invasion, rather than osteomyelitis, was additionally suspected. The mass in the right oropharyngeal wall and right mandible was surgically excised. On postoperative histopathological examination, the mass was finally diagnosed as ACC. As tumor cells were also observed around the inferior alveolar nerve, mandibular bone invasion through the mandibular foramen was suspected. An oropharyngeal ACC invading the mandibular bone through the mandibular foramen is extremely rare. The present case suggests that bone invasion should be considered carefully with several imaging examinations when a malignant tumor such as ACC is observed around the jaw bone.

How Phenotype Guides Management of the Most Common Malignant Salivary Neoplasms of the Larynx?

Salivary gland carcinomas of the larynx are uncommon. Adenoid cystic carcinoma is the most prevalent type of salivary gland carcinoma in this region, although other histologies such as mucoepidermoid carcinoma and adenocarcinomas have been reported. These tumors may present with advanced-stage due to nonspecific symptoms and their relatively slow-growing nature. The index of suspicion for a non-squamous cell carcinoma entity should be high when a submucosal mass is present. An accurate diagnosis is mandatory due to the impact each biologic entity has on treatment and outcome. Data concerning treatment and outcome are scarce, but primary surgery with utmost focus on free surgical margins is the treatment of choice. The role of adjuvant radiotherapy has not been well defined, although there is an agreement that it should be considered in advanced-stage or high-grade disease. This review considers only the most common malignant salivary neoplasms of the larynx with a focus on clinical management of these tumors.