Role of concurrent chemoradiation on locally advanced unresectable adenoid cystic carcinoma

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.

Long-Term Outcomes Following Definitive or Adjuvant Proton Radiotherapy for Adenoid Cystic Carcinoma

Purpose

Adenoid cystic carcinoma (ACC) is a rare malignancy accounting for 1% of all head and neck cancers. Treatment for ACC has its challenges and risks, yet few outcomes studies exist. We present long-term outcomes of patients with ACC of the head and neck treated with proton therapy (PT).

Materials and Methods

Under an institutional review board-approved, single-institutional prospective outcomes registry, we reviewed the records of 56 patients with de novo, nonmetastatic ACC of the head and neck treated with PT with definitive (n = 9) or adjuvant PT (n = 47) from June 2007 to December 2021. The median dose to the primary site was 72.6 gray relative biological equivalent (range, 64-74.4) delivered as either once (n = 19) or twice (n = 37) daily treatments. Thirty patients received concurrent chemotherapy. Thirty-one patients received nodal radiation, 30 electively and 1 for nodal involvement.

Results

With a median follow-up of 6.2 years (range, 0.9-14.7), the 5-year local-regional control (LRC), disease-free survival, cause-specific survival, and overall survival rates were 88%, 85%, 89%, and 89%, respectively. Intracranial extension (P = .003) and gross residual tumor (P = .0388) were factors associated with LRC rates. While the LRC rate for those with a gross total resection was 96%, those with subtotal resection or biopsy alone were 81% and 76%, respectively. The 5-year cumulative incidence of clinically significant grade ≥3 toxicity was 15%, and the crude incidence at the most recent follow-up was 23% (n = 13).

Conclusion

This is the largest sample size with the longest median follow-up to date of patients with ACC treated with PT. PT can provide excellent disease control for ACC of the head and neck with acceptable toxicity. T4 disease, intracranial involvement, and gross residual disease at the time of PT following either biopsy or subtotal resection were significant prognostic features for worse outcomes.

Adenoid cystic carcinoma of distal trachea: A case report

Key Clinical Message

This case report highlights the rarity of distal tracheal adenoid cystic carcinoma and emphasizes the importance of considering it as a differential diagnosis in patients presenting with sustained dyspnea. Early diagnosis and a multidisciplinary approach involving thoracic surgeons, radiation oncologists, and medical oncologists are crucial for optimal treatment planning and patient outcomes. Further research is warranted to better understand the pathogenesis, molecular characteristics, and optimal management strategies for this rare tracheal malignancy.

Abstract

Adenoid cystic carcinoma (ACC) is an unusual malignant neoplasm that mostly arises in the minor salivary glands. It can also occur in various mucous membrane-lined structures, including the trachea. The treatment of choice is surgery in resectable cases, but radiotherapy and chemotherapy are generally utilized for unresectable cases or palliative treatment. In this study, I report my experience with a case of unresectable ACC occurring in a distal trachea treated with concurrent chemoradiotherapy (CCRT), based on the patient's clinical presentation, diagnostic workup, histopathological findings, treatment modalities, and long-term prognosis.

Treatment outcomes of single-fraction stereotactic radiosurgery for adenoid cystic carcinoma: a case series of 55 patients

PURPOSE

This study aimed to analyze the treatment outcomes of single-fraction stereotactic radiosurgery (SRS) for adenoid cystic carcinoma patients.

METHODS

Retrospective analysis was conducted for 55 patients with 66 lesions. SRS intentions were categorized as definitive, adjuvant, salvage, and palliative. Tumor control was defined as local (within 50% isodose line), marginal (outside 50% isodose line), and distant (metastasis outside head/neck).

RESULTS

The median age was 60 years (range 21-85), with 53% males. Tumor origin was head/neck for 88% and trachea/lung for 12%. 61% were recurrent lesions. Median interval from diagnosis to SRS was 14 months. Preceding surgery was performed in 30%. SRS was administered as definitive (30 lesions), adjuvant (13), salvage (19), and palliative (4). SRS was used as a boost to external beam radiation therapy (EBRT) in 39%. Concurrent chemotherapy was administered in 26%. 5-, 10-, and 15-year local control rates were 60%, 33%, and 27%, respectively; local/marginal control rates were 29%, 13%, and 10%. For recurrent lesions treated with SRS without EBRT, 5-year local control rate was 14%, and local/marginal control rate was 5%. For recurrent lesions treated with SRS and EBRT, 5-year local control rate was 100%, and local/marginal control rate was 40%. The rate of distant failure after SRS was 40%. Older age and distant metastasis before SRS were negative factors for overall survival.

CONCLUSION

SRS provided a high rate of local tumor control, but marginal failure was frequent. Integrating SRS with added EBRT exhibits potential for enhancing local and local/marginal tumor control, particularly in recurrent cases.

Long-term follow-up of unresectable adenoid cystic carcinoma of the trachea and bronchus treated with high-dose proton beam therapy: A report of two cases

Adenoid cystic carcinoma (ACC) of the trachea is a rare disease that is slow growing and has a risk of distant metastasis. The standard treatment for ACC of the trachea is surgery, but this tumor is often unresectable. In definitive radiotherapy using photons for unresectable ACC of the trachea, it is sometimes difficult to deliver a sufficient dose to the target without exceeding the tolerable dose to the surrounding normal tissues. Here, we report two cases of ACC of the trachea that received a high dose (74 Gy [relative biological effectiveness]) of proton beam therapy and achieved long-term survival.

A multicenter retrospective analysis of patients with salivary gland carcinoma treated with postoperative radiotherapy alone or chemoradiotherapy

BACKGROUND

The aim of this study was to interrogate if the use of postoperative chemoradiotherapy (POCRT) correlated with superior oncological outcomes for certain subgroups of patients with high-risk salivary gland carcinoma (SGC), compared with postoperative radiotherapy (PORT) alone.

METHODS

This multicenter retrospective study included 411 patients with surgically resected SGC who underwent PORT (n = 263) or POCRT (n = 148) between 2000 and 2015. Possible correlations of clinical parameters with outcomes were examined using the Kaplan-Meier analysis and Cox proportional-hazards regression model.

RESULTS

The median follow-up of survivors is 10.9 years. For the entire cohort, adding concurrent chemotherapy to PORT was not associated with OS, PFS, or LRC improvement. However, patients with nodal metastasis who underwent POCRT had significantly higher 10-year OS (46.2% vs. 18.2%, P = 0.009) and PFS (38.7% vs. 10.0%, P = 0.009) rates than those treated with PORT alone. The presence of postoperative macroscopic residual tumor (R2 resection) was identified as an independent prognosticator for inferior OS (P = 0.032), PFS (P = 0.001), and LRC (P = 0.007). Importantly, POCRT significantly correlated with higher 10-year LRC rates in patients with R2 resection (74.2% vs. 40.7%, P = 0.034) or adenoid cystic carcinoma (AdCC, 97.6% vs. 83.6%, P = 0.039). On multivariate analyses, the use of POCRT significantly predicted superior OS (P = 0.037) and PFS (P = 0.013) for node-positive patients and LRC for patients with R2 resection (P = 0.041) or AdCC (P = 0.005).

CONCLUSIONS

For surgically resected SGC, POCRT was associated with improved long-term OS and PFS for patients with nodal metastasis and superior LRC for patients with R2 resection or AdCC.

Successful Treatment with Definitive Concurrent Chemoradiotherapy Followed by Durvalumab Maintenance Therapy in a Patient with Tracheal Adenoid Cystic Carcinoma

Adenoid cystic carcinoma (ACC) is a rare type of malignant tracheal tumor originating from the secretory glands. Complete surgical resection is the current standard of care for tracheal ACC. However, there have been few case reports of chemoradiotherapy for unresectable tracheal ACC. We herein report a 28-year-old man with unresectable tracheal ACC who received concurrent chemoradiotherapy (CCRT) followed by maintenance therapy with durvalumab. CCRT was completed with a good response and safety, and the patient is currently receiving durvalumab as maintenance therapy. Durvalumab after CCRT can be a treatment option for patients with unresectable tracheal ACC.

Adenoid Cystic Carcinoma of Salivary Glands: A Ten-Year Review and an Assessment of the Current Management, Surgery, Radiotherapy, and Chemotherapy

Adenoid cystic carcinoma (ACC) is a rare cancer that arises from the salivary glands and other sites in the body, such as the lung and breast. Although the tumor accounts for 10% of all salivary gland malignancies, it only accounts for 1% of head and neck malignancies. It can affect both major and minor salivary glands; here, it is called salivary gland adenoid cystic carcinoma or SACC, with a slight predilection to the latter, and commonly manifests between the 6_th and 7_th decades of life. The disease also shows a slight female predilection, with a reported female to male ratio of 3 : 2. Lesions of SACC are often insidious and slow-growing, and symptoms such as pain and altered sensation are frequently associated with advanced stages of the disease. Salivary adenoid cystic carcinoma is characterized by perineural invasion (PNI), a distinctive feature that potentially plays a significant role in the tumor's relapse and recurrence, which is approximately 50%. The disease is not prevalent, and its etiopathogenesis is poorly understood, although several genetic patterns and biomarkers have been linked to its initiation and/or progression. The discovery of these mutations and biomarkers has encouraged several clinical studies to use therapeutic agents to target the specific receptors on the cancer cells to potentially prevent further proliferation of the tumor cells and metastasis of the disease. Diagnosis of SACC is often challenging and frequently requires a combination of clinical examination, imaging, and histopathology. Management of SACC is primarily surgical excision, while radiotherapy has shown to be effective in improving local control in cases with microscopic residual disease. However, treatment of recurrent or metastatic tumors by radiotherapy with or without chemotherapy has so far shown limited success. The aim of this thesis is to provide an update of literature on SACC with a particular focus on the latest management approaches and future trends.

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.

Salivary Gland Cancers

Salivary gland carcinomas are a rare and heterogenous group of cancers with varying underlying biology and clinical behavior. A quickly evolving body of data has advanced the understanding of these tumors, leading to effective therapeutics for several histologic subtypes. Biologically rational clinical trials have developed from an understanding of MYB and NOTCH signaling in adenoid cystic carcinoma. The recognition of androgen receptor signaling and HER2-targeted therapy has offered therapeutic options in non-ACC salivary cancers. The use of TRK inhibitors in salivary secretory carcinoma has led to exceptional responses. Immunotherapy is an exciting new therapeutic avenue that requires further exploration.

Concurrent chemoradiotherapy for locally advanced unresectable adenoid cystic carcinoma of head and neck: experience from a single institute

PURPOSE

To analyze the outcome of locally advanced unresectable adenoid cystic carcinoma (ACC) of head and neck treated with radical concurrent chemoradiotherapy (CRT) at a single tertiary care centre.

METHODS

Between 2011 and 2018, 23 patients with locally advanced unresectable ACC of head and neck treated with non-surgical radical treatment with concurrent chemoradiotherapy were evaluated for outcome and toxicity. All but one patient received cisplatin-based concurrent chemotherapy and 74% of patients were treated with intensity-modulated radiotherapy.

RESULTS

Median follow-up was 53 months (range 3-115 months). Following treatment, 11 patients achieved complete response (47.8%) and of the 12 patients with residual disease, 7 patients additionally had disease stabilization without local progression. Overall 15 patients had disease progression. Median time to progression was 28 months (range 6-67 months). The 3-year and 5-year overall survival, local progression-free survival (LPFS) and distant progression-free survival (DPFS) were 78%, 79.7%, 67.4% and 63%, 50.9%, 48.6%, respectively. Acute grade 3 mucositis was observed in three patients, and one patient additionally developed grade 4 neutropenia with subsequent complete recovery. No grade 3 or higher late toxicity was observed.

CONCLUSION

Radical concurrent chemoradiotherapy is a promising treatment option in locally advanced unresectable ACC with acceptable toxicity.