Abstract
Purpose
The purpose of the study was to evaluate the treatment results of adenoid cystic carcinoma (ACC) of the airway at a single institution during a 30-year period.
Materials and methods
All cases of ACC of the airway over a 30-year period at one tertiary care institution were reviewed retrospectively. The demographics, treatment modalities, pathologic characteristics, and outcomes were evaluated.
Results
Eleven patients were treated for ACC of the airway with an age range of 25 to 72 years (median, 48 years). Six patients presented with ACC in the larynx, and 5 patients had ACC of the trachea. All patients underwent surgical excision and radiation; 9 of 11 patients had postoperative external beam radiation, 1 patient had preoperative external beam radiation, and the remaining patient had postoperative neutron beam therapy. Four patients with tracheal ACC and none with laryngeal ACC had microscopic or grossly positive margins after surgery ( P = .048). Eighty percent of patients had perineural invasion on pathology. Two patients with tracheal ACC had local recurrence of disease, which occurred at 1 and 10 months postoperatively. One patient with laryngeal ACC died of distant metastatic disease at 16 months. Follow-up varied from 4 to 168 months (median, 31 months).
Conclusions
We report high disease-free survival rates for ACC of the airway in patients who underwent definitive surgical resection followed by postoperative radiation. There is a higher risk for local recurrence and positive surgical margins with distal tracheal location. Distant disease ultimately determines survival.
1
Introduction
Adenoid cystic carcinoma (ACC) or cylindroma is a malignant tumor of the salivary glands and was first reported by Billroth in 1856 . It is most commonly found in the parotid gland and accounts for 10% of tumors of the head and neck. It is a tumor of major and minor salivary glands and can therefore occur in any head and neck site containing salivary gland tissue. Adenoid cystic carcinoma typically presents with late metastases most commonly to the lungs , but can also metastasize to the brain, bone, liver, thyroid, and spleen . It is also known for its neurotropic tendency, accounting for local regional recurrences many years after initial presentation and treatment .
Adenoid cystic carcinoma of the airway is much less common and originates from the submucosal glands of the tracheobronchial tree . Most patients present with dyspnea and wheezing from central airway obstruction. As in other more common head and neck subsites, surgical excision with postoperative radiotherapy is considered the definitive treatment of airway ACCs ; however, resectability often becomes difficult especially in patients with distal tracheal involvement . Adenoid cystic carcinoma of the airway tends to have lower disease-free survival (DFS) and can be divided into laryngeal (including the subglottis) and tracheal subsites.
Laryngeal ACC is extremely rare. A review of the literature shows approximately 40 cases reported in the past 41 years . Patients tend to present with symptoms of long duration due to slow progressive growth of the ACC. Even after treatment, laryngeal ACC is reported to have a tendency for local recurrence and the eventual development of pulmonary metastasis . Treatment recommendations based on small case series consist of surgical resection and ionizing radiation to achieve local control. Mortality is typically thought to be the result of metastatic disease . Elective neck dissection has been suggested only for clinical lymph node disease.
Tracheal ACC, although also uncommon, has been reported more frequently. It is the second most common primary malignancy of the trachea after squamous cell carcinoma and is usually found in younger patients. Tracheal ACC has been shown in at least one study to be more prevalent in women . Adenoid cystic carcinoma, as in other head and neck sites, is known to metastasize much later in the course of the disease. However, palliation of tracheal tumors has been reported for many years using laser bronchoscopy and stenting . Adenoid cystic carcinoma has a propensity to spread submucosally and along perineural bundles, making tracheal tumors difficult to resect .
Because of the rarity of ACC in the airway, prospective multi-institutional studies to evaluate prognostic factors, treatment, and outcome are not feasible. Therefore, institutional case series are an important guide to therapeutic approach. We present the demographics, treatment modalities, histopathology, and outcomes for patients with ACC of the airway reviewed at one institution over the past 30 years.
2
Methods
After obtaining institutional review board approval, a retrospective chart review of all patients treated for ACC of the airway (larynx and trachea) at a tertiary care academic center between 1980 and 2010 was performed. Patients were identified through a computer-assisted search performed by the UCLA Tumor Registry in the Department of Pathology. The laryngeal subsite was defined as the area between epiglottis proximally and the cricoid cartilage distally, and the tracheal subsite was defined as the airway distal to the cricoid cartilage.
The medical records of the patients were reviewed to determine patient age, risk factors, location, treatment modalities received, surgical approach, surgical margins, surgical pathology, and outcome. A single head and neck pathologist reviewed the surgical pathology of all patients for evidence of histologic grade, perineural invasion (PNI), and microscopically positive surgical margins. Grade was based on the percentage of solid components seen in the tumor, with 0% solid component corresponding to low grade, less than 30% corresponding to intermediate grade, and greater than 30% representing high grade . A telephone interview was conducted with patients or family members in certain cases to obtain additional follow-up.
Clinical factors (eg, PNI, margins) were compared between the sites (larynx and trachea) using Fisher exact test. Time to first recurrence (distant or local) was compared between the sites using the log-rank test. The Kaplan-Meier method was used to construct DFS curves for the sites. Splus version 6 (TIBCO Inc, Palo Alto, CA) was used to perform all statistical analyses.
2
Methods
After obtaining institutional review board approval, a retrospective chart review of all patients treated for ACC of the airway (larynx and trachea) at a tertiary care academic center between 1980 and 2010 was performed. Patients were identified through a computer-assisted search performed by the UCLA Tumor Registry in the Department of Pathology. The laryngeal subsite was defined as the area between epiglottis proximally and the cricoid cartilage distally, and the tracheal subsite was defined as the airway distal to the cricoid cartilage.
The medical records of the patients were reviewed to determine patient age, risk factors, location, treatment modalities received, surgical approach, surgical margins, surgical pathology, and outcome. A single head and neck pathologist reviewed the surgical pathology of all patients for evidence of histologic grade, perineural invasion (PNI), and microscopically positive surgical margins. Grade was based on the percentage of solid components seen in the tumor, with 0% solid component corresponding to low grade, less than 30% corresponding to intermediate grade, and greater than 30% representing high grade . A telephone interview was conducted with patients or family members in certain cases to obtain additional follow-up.
Clinical factors (eg, PNI, margins) were compared between the sites (larynx and trachea) using Fisher exact test. Time to first recurrence (distant or local) was compared between the sites using the log-rank test. The Kaplan-Meier method was used to construct DFS curves for the sites. Splus version 6 (TIBCO Inc, Palo Alto, CA) was used to perform all statistical analyses.
3
Results
3.1
Patients
Eleven patients (8 women and 3 men) were identified in the registry with ACC of the larynx or trachea. The supraglottic larynx and glottic larynx were the primary sites in 4 patients, the subglottis in 2 patients, and the trachea in 5 patients ( Table 1 ). In the 4 laryngeal ACCs, the original tumors appeared to originate in one patient from the paratracheal area with invasion into the larynx, the right aryepiglottic fold in another patient, and the cricoid cartilage with involvement of the right true vocal cord in the other patients. The subglottic tumors were located in the area defined inferiorly by the cricoid cartilage. The 5 patients with tracheal ACCs had tumors originating from the left mainstem bronchus in one patient, the proximal trachea in another patient, and the distal trachea in the other 3 patients. None of the patients had evidence of distant metastatic disease at the time of diagnosis. Patients’ characteristics, treatments, and outcomes are summarized in Table 2 .
| Site | No. of patients (%) |
|---|---|
| Larynx | 4 (36) |
| Subglottis | 2 (18) |
| Trachea | 5 (45) |
| Patient no. | Location | Treatment | Surgery type | Surgical margins ⁎ | Radiation dose, cGy | PNI | Grade | Recurrence | Months to recurrence | Length of follow-up, mo |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Larynx | Sx + XRT | TL, pharyngectomy, ND, FF | Negative | 6000 | Yes | II | None | 31 | |
| 2 | Larynx | Sx + XRT | Supraglottic laryngectomy | Negative | 5940 | No | III | None | 21 | |
| 3 | Larynx | Sx + XRT | TL | U/k | U/k | U/k | U/k | None | 168 | |
| 4 | Larynx | Sx + XRT | TL | Negative | 6400 | Yes | III | Distant | 12 | 16 |
| 5 | Larynx | Sx + XRT | Cricotracheal resection | Negative | 5940 | Yes | I | None | 72 | |
| 6 | Larynx | Sx + XRT | TL, pharyngectomy, FF | Negative | U/k | Yes | I | None | 8 | |
| 7 | Trachea | Preop XRT + Sx | Pneumonectomy, carinal resection | Positive | U/k | Yes | I | Local | 10 | 10 |
| 8 | Trachea | Sx + XRT | Tracheal resection | Positive | 6300 | Yes | II | None | 4 | |
| 9 | Trachea | Sx + XRT | Tracheal resection | Negative | 5040 | Yes | II | None | 120 | |
| 10 | Trachea | Sx + XRT | Tracheal resection | Positive | 6480 | Yes | I | None | 74 | |
| 11 | Trachea | Sx + neutron RT | Tracheal resection, esophagectomy | Positive | N/a | No | I | Local | 1 | 34 |
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