Predictors of Distant Metastasis and Survival in Adenoid Cystic Carcinoma of the External Auditory Canal

An Improved Staging System of Adenoid Cystic Carcinoma in the External Auditory Canal

OBJECTIVE

The purpose of this study was to define an improved staging system for adenoid cystic carcinoma (ACC) in the external auditory canal (EAC) based on biological behaviors, image findings, and the prognosis of patients with ACC in the EAC.

STUDY DESIGN

A retrospective study.

SETTING

A single center data.

METHODS

We performed a single-institution retrospective review of 154 patients with ACC in the EAC between January 2004 and September 2021. Risk factors associated with disease-free survival (DFS) and cancer-specific survival (CSS) of ACC in the EAC were identified using univariate and multivariate cox regression analysis. Then an improved staging system was proposed and compared with the Pittsburgh-modified tumor, node, and metastasis (TNM) staging system for statistical differences in DFS and CSS.

RESULTS

An improved staging system of ACC in the EAC was defined, in which stage T4 were subclassified into T4a and T4b and were statistically different from the Pittsburgh-modified TNM staging system in DFS and CSS. We also found that the dura mater, facial nerve, sigmoid sinus, deep lobe of parotid gland, and parapharyngeal space involvement were significantly associated with poor prognosis of ACC in the EAC.

CONCLUSION

The improved staging system is more accurate in predicting survival prognosis than Pittsburgh-modified TNM staging system for patients with ACC in the EAC, and may provide more efficient guidance of treatment strategy.

SUMMARY

The improved staging system of ACC in the EAC is more accurately to predict survival prognosis, and provide guidance of treatment plan than Pittsburgh-modified TNM staging system.

LEVEL OF EVIDENCE: 4

Metastasis to the External Auditory Canal: A Systematic Review

OBJECTIVE

To systematically review the literature and understand the behavior, diagnosis, management, and mortality of metastasis to the external auditory canal (EAC).

DATABASES REVIEWED

PubMed/Medline, EMBASE, Web of Science.

METHODS

Studies from 1948 to June 2023 describing metastasis to the EAC were included. Non-English literature was excluded. Data extraction: Study design, age, sex, pathology, primary site, staging, additional sites of metastasis, time to EAC metastasis from diagnosis, time from diagnosis of EAC metastasis to death, symptoms, exam and imaging findings, and management.

RESULTS

Data were synthesized qualitatively with means calculated. Thirty-two studies met the criteria, totaling 37 patients with EAC metastasis. Mean age was 58 years; 73% were male. The most common pathologies were adenocarcinoma (37.8%), acute myelogenous leukemia (8.1%), and renal cell carcinoma (8.1%). Sites of primary malignancy were hematologic (10.8%), breast (8.1%), esophagus (8.1%), renal (8.1%), and prostate (8.1%). Within the temporal bone, 73% had isolated EAC metastasis. Median time to EAC metastasis from the diagnosis of primary malignancy was 18 months. Metastasis to the EAC was the first presentation of malignancy in 21.6% of patients. Median time to death was 4.5 months. Symptoms included hearing loss (59.5%), otalgia (27.0%), otorrhagia (24.3%), facial paralysis (21.6%), otorrhea (16.2%), and aural fullness (13.5%). On imaging, bony erosion was present in 50% of cases. Treatment was primarily palliative with excision and radiation.

CONCLUSIONS

EAC metastasis has a distinct presentation from other temporal bone subsites. Early biopsy to establish a diagnosis and intervene is critical.

Adenoid cystic carcinoma of submandibular gland: Emphasis on locoregional metastasis and prognosis

OBJECTIVES

To analyze the clinicopathological features, locoregional or distant metastasis, and prognosis of adenoid cystic carcinoma of submandibular gland (SMG-AdCC).

METHODS

The clinicopathological data of 80 patients with SMG-AdCC from January 2005 to December 2017 were analyzed retrospectively, and the relationships between different parameters of SMG-AdCC and its locoregional or distant metastasis or prognosis were analyzed.

RESULTS

As of December 2019, 41 patients (51.25%) were tumor-free, while 20 patients were found to be living with tumors. The locoregional metastasis rate of grade II-III SMG-AdCC were found to be significantly higher than that of grade I. The five-year DFS and OS rates were 70.8% and 87.1%, respectively. Univariate analysis showed that clinical size, extraglandular extension, pathological grade, pathological node (pN) status, and perineural invasion were correlated with DFS. Multivariate Cox regression analysis showed that pathological grade and extraglandular extension were independent prognostic factors for DFS; pN status and extraglandular extension were independent prognostic factors impacting OS.

CONCLUSION

The pathological grade is a risk factor for locoregional metastasis of SMG-AdCC. Pathological grade, pN status, and status of extraglandular extension are independent prognostic factors for DFS/OS in SMG-AdCC patients.

Risk Factors for Locoregional Recurrence and Distant Metastasis in 143 Patients with Adenoid Cystic Carcinoma of the External Auditory Canal

AIMS

Adenoid cystic carcinoma (ACC) grows slowly and is characterised by potential recurrence and metastasis to distant organs. This study aimed to evaluate the risk factors for locoregional recurrence (LRR) and distant metastasis in patients with ACC of the external auditory canal (EAC).

MATERIALS AND METHODS

Demographic, pathological, therapeutic and survival data of 143 patients with EAC ACC were reviewed in this study. Univariate and multivariate Cox proportional hazard regression analyses were carried out to determine the risk factors for LRR and distant metastasis. Factors associated with overall survival after LRR and distant metastasis were also analysed.

RESULTS

During a median follow-up of 49 months, 31 of 143 patients were observed with LRR and 34 developed distant metastasis. Bone invasion and histological subtype were independent risk factors for locoregional recurrence-free survival. T stage and LRR were independent risk factors for distant metastasis-free survival. Salvage surgery and adjuvant radiotherapy or chemoradiotherapy for LRR resulted in better survival, whereas extrapulmonary metastasis and LRR were associated with a higher risk of poor survival after distant metastasis.

CONCLUSION

Patients with distant metastases, especially those with LRR, are at significant risk of poor prognosis. Our findings emphasise the importance of long-term regular follow-up and recommend surgical intervention with radiotherapy for recurrent EAC ACC.

The Role of Parotid Gland Invasion in Adenoid Cystic Carcinoma of the External Auditory Canal

OBJECTIVE

This study aimed to investigate the significance of parotid gland invasion in predicting distant metastasis of adenoid cystic carcinoma in the external auditory canal.

STUDY DESIGN

Single-institution retrospective cohort study.

METHODS

A retrospective review of patients with adenoid cystic carcinoma of the external auditory canal who underwent surgery was performed. Information on patient demographics, parotid gland invasion, tumor stage, perineural invasion, lymphovascular invasion, and follow-up data were collected and analyzed.

RESULTS

One hundred twenty-nine patients were identified for review. Parotid gland invasion was noted in 45 patients (34.9%). Parotid gland invasion was significantly associated with tumor stage, perineural invasion, distant metastasis, and postoperative adjuvant therapy. Distant metastasis was noted in 30 patients (23.3%). Multivariate Cox proportional hazards analysis identified parotid gland invasion as an independent risk factor for predicting distant metastasis. The 5-year distant metastasis-free survival rate was 83.6% for patients without parotid gland invasion and 61.8% for patients with parotid gland invasion (p = 0.010).

CONCLUSIONS

The parotid gland invasion rate is relatively high in adenoid cystic carcinoma of the external auditory canal and is significantly related to tumor stage. Parotid gland invasion is associated with worse distant metastasis-free survival.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:419-425, 2024.

Intraparotid lymph node metastasis affects distant metastasis in parotid adenoid cystic carcinoma

To evaluate the relationship between factors of metastatic intraparotid lymph node (IPLN) and distant metastasis in parotid adenoid cystic carcinoma (ACC). Patients with surgically treated parotid ACC were retrospectively enrolled, and primary outcome variable was distant metastasis free survival (DMFS). The effect of factors of metastatic IPLN on DMFS was evaluated using Cox model. In total, 232 patients were included. Extranodal extension of IPLN and cervical lymph nodes did not impact the DMFS, and the 7th but not 8th AJCC N stage was associated with DMFS. Groups of 0 and 1 metastatic IPLN had comparable DMFS, but presence of 2+ positive IPLN was related to increased worse DMFS (p = 0.034, HR 2.09). A new N stage (0 vs 1-2 vs 3+) based on total positive lymph node number exhibited better C-index than traditional N stage. IPLN metastasis increased the risk of distant metastasis, and the impact was mainly determined by the number of metastatic IPLN. Our proposed N stage provided better DMFS prediction than the 8th AJCC N classification.

Clinical outcome and prognostic factors in adenoid cystic carcinoma of the external auditory canal: proposal for a refined T-stage classification system

PURPOSE

Although adenoid cystic carcinoma (ACC) of the external auditory canal (EAC) has a different pathophysiology from squamous cell carcinoma, the same staging system is used. The aim of this study was to propose a refined staging system, which is more suitable for ACC of the EAC.

METHODS

A total of 25 patients who were diagnosed with ACC of the EAC were reviewed. The modified Pittsburgh staging system (mPSS) that is universally used for temporal bone malignancy was refined for ACC (rPSS). The limited (< 0.5 cm) lateral soft tissue involvement was classified as T1 and extensive (≥ 0.5 cm) lateral soft tissue involvement as T2. The disease-free survival rate (DFSR) was assessed in the patients who underwent surgical treatment according to two staging systems; mPSS and rPSS.

RESULTS

When staging using mPSS, most patients (96.0%, n = 24) were classified as T4. However, when rPSS was used, T1, T2, T3, and T4 stage occupied 36.0% (n = 9), 40.0% (n = 10), 12.0% (n = 3), 12.0% (n = 3), respectively. There was no difference in DFSR according to the T stage using mPSS (p = 0.466). However, when rPSS was used, the DFSR showed significant correlation with the T stage (p = 0.032).

CONCLUSIONS

Clinical T stage of mPSS was not sufficient to predict survival rate in ACC of the EAC, and we propose that the information on the lateral soft tissue involvement needs to be added to the existing staging system.

Heterogeneity of Synchronous Lung Metastasis Calls for Risk Stratification and Prognostic Classification: Evidence from a Population-Based Database

The epidemiology and associated potential heterogeneity of synchronous lung metastasis (sLM) have not been reported at a population-based level. Cancer patients with valid information about sLM status in the Surveillance, Epidemiology, and End Results database were enrolled. The prevalence of sLM, with a 95% confidential interval, and median survival of sLM, with interquartile range, were calculated and compared by Chi-square analyses and log-rank tests by primary cancer type and clinicopathological factors. Furthermore, the risk factors of sLM development were identified by multivariate logistic regression. Among 1,672,265 enrolled cases, 3.3% cases were identified with sLM, with a median survival of 7 months. Heterogeneity in prevalence and prognosis in sLM was observed among different primary cancers, with the highest prevalence in main bronchus cancer and best survival in testis cancer. Higher prevalence and poorer prognosis were observed in the older population, male population, African American, patients with lower socioeconomic status, and cases with advanced T stage, N stage, or more malignant pathological characteristics. Race, age, T stage, N stage, metastasis to other sites, insurance status and marital status were associated with sLM development (p < 0.001). The current study highlights the heterogeneity of the prevalence and prognosis in patients with sLM.

Treatment and survival outcomes of ceruminous carcinomas of the external auditory canal: a SEER database analysis and literature review

Ceruminous carcinomas of the external auditory canal (EAC), encompassing adenoid cystic carcinoma (ACC), ceruminous adenocarcinoma (CA), and mucoepidermoid carcinoma (MEC), are extremely rare with little known regarding the influence of demographics, tumor characteristics, and treatment on survival. This study aimed to summarize existent data and describe prognostic factors affecting survival in ceruminous carcinoma. Cases of ceruminous carcinoma of the EAC in the Surveillance, Epidemiology, and End Results (SEER) database were analyzed to provide demographic, cancer-related, and treatment data and assess their influence on disease-specific and overall survival. A literature review was also performed. No significant difference in overall survival (OS) existed for localized versus regional disease, tumor type, or use of radiation therapy. In those with ACC, distant disease had a lower OS compared to regional disease. On review of the literature, local recurrence was a common finding with a low risk for nodal metastasis in ACC and CA. In conclusion, local recurrence was common despite aggressive surgical intervention (± radiation therapy); overall survival was unaffected by radiation therapy, tumor type, or local versus regional disease; and more cases of MEC are needed for analysis.