Biology of Adenoid Cystic Carcinoma of the Tracheobronchial Tree and Principles of Management

Adenoid Cystic Carcinoma of the Minor Salivary Glands: A Systematic Review and Meta-Analysis of Clinical Characteristics and Management Strategies

BACKGROUND

Intraoral adenoid cystic carcinoma (ACC) arising from minor salivary glands (MSG) is a rare malignancy associated with delayed diagnosis and unfavorable outcomes. This study aimed to comprehensively review ACC of MSGs, focusing on clinical characteristics, imaging modalities, treatment approaches, and long-term outcomes.

METHODS

A systematic search was conducted in PubMed, Web of Science, and MEDLINE databases to identify relevant articles reporting cases of ACC of MSGs between January 1997 and March 2023. The study was registered in PROSPERO (ID: CRD42023449478). A total of 10 studies that met the inclusion criteria were selected for critical review. In total, 902 patients were diagnosed with ACC of MSGs with an age range of 44.3 to 63 years, and an average age of 56.6 years. The female to male ratio ranges from 1:1 to 2.4:1. Regarding the primary site of ACC, the palate was the most common location, accounting for 30.5% to 83.3%, followed by the buccal mucosa, floor of the mouth, and lip and the retromolar area. For histology, the solid mass pattern was the most prevalent, seen in 95.2% of patients, followed by the cribriform pattern. Regarding treatment modalities, surgery was the most common approach, applied in 76.3% of cases, with a combination of surgery and radiotherapy used in 29.0% of cases. A smaller fraction, 3.2%, received a combination of surgery, chemotherapy, and radiotherapy, and 8.3% underwent radiotherapy alone. Local recurrence rates varied between 1% and 28.5%, and distant metastasis occurred in 18.2% to 33.3% of cases, predominantly to lymph nodes (14.5%). An analysis of overall survival across various stages and patient numbers indicated a 5-year survival rate of 68.0%. The findings of this study provide valuable insights for physicians in making treatment decisions and emphasize the need for ongoing research and collaborative clinical efforts to improve the management and outcomes of this challenging disease.

CONCLUSION

ACC of MSGs is a multifaceted condition typically manifesting as asymptomatic enlargement and ulceration. This disease is marked by distinct histopathological patterns and perineural invasion (PNI). Recognizing these distinctive aspects is key in shaping the treatment plan, which can range from surgical procedures to radiation therapy, chemotherapy, and evolving targeted treatments. Continuous research and collaborative clinical efforts remain critical for ongoing progress in the treatment and management of this challenging condition.

The Novel Application of Robotic-Assisted Bronchoscopy Combined with Photodynamic Therapy for Adenoid Cystic Carcinoma of the Trachea

Robotic platforms have been widely used in the various fields of clinical diagnosis and therapy of diseases in the past decade. Robotic-assisted bronchoscopy (RAB) demonstrates its advantages of visibility, flexibility, and stability in comparison to conventional bronchoscopic techniques. Improving diagnostic yield and navigation yield for peripheral pulmonary lesions has been defined; however, RAB platform of treatment was not reported. In this article, we report a case of a 52-year-old woman who was diagnosed with the tracheal adenoid cystic carcinoma and recurred in the second postoperative year, leading to the involvement of the entire tracheal wall and lumen obstruction. Since the lesion was inoperable, we combined RAB and photodynamic therapy (PDT) for the patient. The potential advantages of using RAB for PDT delivery include precise light irradiation of target lesions and stable intra-operative control over the long term. This is a novel application of RAB combined with PDT for airway diseases. The case report may provide a new insight into the diagnosis and treatment of pulmonary diseases. In addition to improving the diagnostic rates, the RAB platform may also play an important role in the treatment of airway and lung disease in the future.

Molecular Biology and Therapeutic Targets of Primitive Tracheal Tumors: Focus on Tumors Derived by Salivary Glands and Squamous Cell Carcinoma

Primary tracheal tumors are rare, constituting approximately 0.1-0.4% of malignant diseases. Squamous cell carcinoma (SCC) and adenoid cystic carcinoma (ACC) account for about two-thirds of these tumors. Despite most primary tracheal cancers being eligible for surgery and/or radiotherapy, unresectable, recurrent and metastatic tumors may require systemic treatments. Unfortunately, the poor response to available chemotherapy as well as the lack of other real therapeutic alternatives affects the quality of life and outcome of patients suffering from more advanced disease. In this condition, target therapy against driver mutations could constitute an alternative to chemotherapy, and may help in disease control. The past two decades have seen extraordinary progress in developing novel target treatment options, shifting the treatment paradigm for several cancers such as lung cancer. The improvement of knowledge regarding the genetic and biological alterations, of major primary tracheal tumors, has opened up new treatment perspectives, suggesting the possible role of biological targeted therapies for the treatment of these rare tumors. The purpose of this review is to outline the state of knowledge regarding the molecular biology, and the preliminary data on target treatments of the main primary tracheal tumors, focusing on salivary-gland-derived cancers and squamous cell carcinoma.

[Bronchoscopic treatment of malignant central airway obstruction: A cohort study, long-term survival and complications]

INTRODUCTION

Interventional bronchoscopy is now the standard treatment for tracheobronchial narrowing due to tumor. The objective of our study was to analyze long-term survival and complications occurring in patients with malignant airway obstruction.

METHODS

We retrospectively studied the data from 93 patients treated between 2008 and 2019.

RESULTS

One hundred and eleven therapeutic bronchoscopies were performed. Sixty-seven patients had primary lung cancer, in 17 had tumors of another origin and 9 patients had benign or local lung tumors. Thulium laser was frequently used prior to tumor enucleation and to restore hemostasis. Seventy-one silicone stents were inserted. The death rate at the time of the procedure was 1.8% and immediate complication occurred in 9.9% of the patients. Long-term survival was significantly better for patients with cancer from other origins than in those with primary lung cancer (615.5days versus 177.9days). On the other hand, there was no significant difference in long-term survival between patients with locally advanced and metastatic lung cancer with endobronchial lesions treated by stent and those who were not (234.2days versus 164.6days). All patients with benign or with locally malignant tumors were still alive.

CONCLUSION

Therapeutic bronchoscopy increases the long-term survival of patients with malignant airway obstruction. The risk-benefit ratio was favorable.

Contrast-enhanced CT longitudinal tail sign as a marker of positive resection margins in adenoid cystic carcinoma of the central airway

Background

Due to submucosal infiltration’s biological nature along the airway, adenoid cystic carcinoma (ACC) frequently leaves positive surgical margins. This study evaluated the clinicopathologic, and computed tomography (CT) features for predicting surgical margin status in central airway ACC.

Methods

We retrospectively analyzed the files of 71 patients with ACC of the central airway proven by histopathology and surgery who had presented between January 2010 and December 2018. All patients were classified into positive and negative surgical margin groups according to margin status. Univariate analysis and multivariable logistic regression models were then performed to compare demography, histopathology, and CT characteristics between ACC patients with positive and negative margins.

Results

After surgical resection, 59 (83.1%) patients had positive margins, and 12 (16.9%) had negative margins. The contrast-enhanced CT (CECT) longitudinal tail sign (LTS) was identified in 55 of 59 (93.2%) patients with positive margins and was the only feature that had a significant association with positive margins (odds ratio 41.250, 95% CI: 7.886–215.767; P<0.001). Moreover, positive margins in upper or/and lower directions were associated with the LTS in corresponding directions (P<0.001).

Conclusions

Most central airway ACC patients exhibited positive margins following surgery. The appearance of the LTS on CECT was significantly associated with positive margins and could help preoperatively predict the submucosal invasion of ACC.

Patterns of Care and Outcomes of Primary Adenoid Cystic Carcinoma of the Trachea

OBJECTIVE

Primary tracheal malignancies are relatively rare cancers, representing 0.1% to 0.4% of all malignancies. Adenoid cystic carcinoma (ACC) is the second most common histology of primary tracheal malignancy, after squamous cell carcinoma. This study aims to analyze demographic characteristics and potential influencing factors on survival of tracheal ACC (TACC).

METHODS

This was a retrospective cohort study utilizing the National Cancer Database (NCDB). The NCDB was queried for all cases of TACC diagnosed from 2004 to 2016 (n = 394). Kaplan-Meier (KM) and Cox proportional-hazards models were used to determine clinicopathological and treatment factors associated with survival outcomes.

RESULTS

Median age of diagnosis was 56 (IQR: 44.75-66.00). Females were affected slightly more than males (53.8% vs 46.2%). The most prevalent tumor diameter range was 20 to 39 mm (34.8%) followed by greater than 40 mm in diameter (17.8%). Median overall survival (OS) was 9.72 years with a 5- and 10-year OS of 70% and 47.5%, respectively. Localized disease was not associated with a survival benefit over invasive disease (P = .388). The most common intervention was surgery combined with radiation therapy (RT) at 46.2%, followed by surgery alone (16.8%), and standalone RT (8.9%). When adjusting for confounders, surgical resection was independently associated with improved OS (HR 0.461, 95% CI 0.225-0.946). Tumor size greater than 40 mm was independently associated with worse OS (HR 2.808; 95% CI 1.096-7.194).

CONCLUSION

Our data suggests that surgical resection, possibly in conjunction with radiation therapy, is associated with improved survival, and tumor larger than 40 mm are associated with worse survival.

Clinical features, treatment and outcomes in patients with tracheal adenoid cystic carcinoma: a systematic literature review

Background

Primary tracheal adenoid cystic carcinoma (TACC) is rare and originates from the minor salivary gland. Biologically, TACC results in delayed presentation, and the therapeutic effects of multimodal treatment differ across individuals. This study aimed to review cases of TACC to identify clinical features, imaging modalities, treatment, and patient outcomes across follow-ups.

Methods

The PubMed, Web of Science and MEDLINE databases were searched to identify articles reporting cases of TACC. The study variables included in the analysis were patient demographics, biological characteristics, presenting symptoms, imaging modalities, treatments, follow-up times and survival outcomes.

Results

A total of 76 articles and 1252 cases were included in this review. The most common presenting symptom was dyspnoea (86.0%), followed by cough (58.0%). Surgery alone (40.9%), surgery with postoperative radiotherapy (36.4%) and radiotherapy alone (19.2%) were used most frequently treatments modalities. Of the 1129 cases with disease control and survival data, there was no evidence of disease in 78.7%, local recurrence was reported in 3.8%. Distant metastasis rate was 24.9% of 418 reported cases, lung (44.2%) was the most commonly involved organ. The 5, 10 years survival rate of patients treated with surgery alone and surgery with postoperative radiotherapy were 86.4%, 55.6% and 97.3%, 44.4%, respectively.

Conclusion

TACC most common presenting symptoms were dyspnoea, cough and shortness of breath. Surgery alone and surgery with postoperative radiotherapy are predominant treatment modalities. Both seems to provide a good result in term of disease control and long-term survival rate in patients with TACC.

Adenoid cystic carcinoma cytology: Salivary gland and nonsalivary gland

OBJECTIVES

Adenoid cystic carcinoma (ACCA) is an uncommon primary malignancy of salivary glands and rarely nonsalivary tissue. This study aims to evaluate the diagnostic accuracy of ACCA on fine needle aspiration (FNA) material and the associated challenges.

METHODS

A search on electronic pathology database from 2006 to 2016 at The Johns Hopkins Hospital found 83 cytology specimens diagnosed as ACCA, 49 with histology follow-up.

RESULTS

Fifty-two females and 31 males were found ranging from 37 to 95 years old (mean 62.5). The tumor size was 1 to 11.5 cm (mean 3.4). FNAs were performed on 46 salivary glands (54.88%), 12 head and neck masses (14.45%), 9 lymph nodes (10.84%), 9 tracheas/lungs (10.84%), 4 vaginal/perineum/gluteal masses (4.82%), and one for each kidney, liver and abdominal/pelvic mass (1.21%). 83 FNA diagnoses revealed 3 nondiagnostics (3.61%), 20 neoplasms with unspecified features (24.10%), 30 basaloid neoplasms (36.14%), 18 ACCA (21.69%), and 12 other malignancies (14.46%). The accuracy of FNA in diagnosis of ACCA comparing to histologic follow-up in 49 cases was 87.5% sensitivity, 66.67% specificity, with 92.11% positive predictive value and 54.55% negative predictive value. The most common mimicker was pleomorphic adenoma.

CONCLUSION

ACCA can be diagnosed not only in the salivary gland FNAs, but also respiratory tract, intra-abdominal, kidney, and gynecologic regions. FNA is a preferred technique to assess mass lesions. However, a diagnosis of ACCA on FNA material should be rendered with caution since there are benign and malignant neoplasms with overlapping features. Awareness of prior medical history and ancillary studies can improve the diagnosis.

Intensity-modulated radiotherapy for paranasal sinuses and base of skull tumors

Paranasal sinus and skull base tumors are rare aggressive head and neck cancers, and typically present in the locally advanced stages. As a result, achieving wide surgical resection with clear margins is a challenge for these tumors, and radiotherapy is thus usually indicated as an adjuvant modality following surgery to optimize local control. Given the integral role of radiotherapy in the management of this subgroup of head and neck tumors, the advent of intensity-modulated radiotherapy (IMRT) has led to substantial improvement of clinical outcomes for these patients. This is primarily driven by the improvement in radiation dosimetry with IMRT compared to conventional two dimensional (2D)- and 3D-techniques, in terms of ensuring dose intensity to the tumor target coupled with minimizing dose exposure to critical organs. Consequently, the evident clinical benefits of IMRT have been in reduction of normal tissue toxicities, ranging from critical neurological symptoms to less debilitating but bothersome symptoms of eye infections and radiation-induced skin changes. Another domain where IMRT has potential clinical utility is in the management of a subset of non-resectable T4 paranasal sinus and skull base tumors. For these inoperable lesions, the steep dose-gradient between tumor and normal tissue is even more advantageous, given the crucial need to maintain dose intensity to the tumor. Innovative strategies in this space also include the use of induction chemotherapy for patient selection. In this review, we summarized the data for the aforementioned topics, including specific discussions on the different histologic subtypes of paranasal sinus and skull base tumors.