Tracheal Tumors

Table 2.

		ACC	SCC	χ2 p Value
Sex (%)
	Female	53	32	0.004
	Male	46	68
Mean age(median), years		49 (47)	61 (62)
Comorbidities(%)
	Smoker	45	89	<0.001
	Hypertension	17	29	0.02
	EtOH use	5	18	<0.001
	Past MI	2	13	0.001
	Diabetes mellitus	2	12	0.002
	Steroid use	7	7	0.812
	Angina	3	6	0.238
	Arrhythmia	3	5	0.356
	Prior stroke	2	3	0.702
Prior cancers (%)
	Lung	1	15	<0.001
	Larynx	0	7	0.001
	Head and neck	0	4	0.024
	Colon	1	1	0.562
	Prostrate	1	1	0.562
	Oropharynx	0	1	0.156
	Other	0	7	0.001
Symptoms(%)
	Dyspnea	65	50	0.014
	Cough	55	52	0.626
	Hemoptysis	29	60	<0.001
	Wheeze	44	27	0.003
	Stridor	21	27	0.2
	Hoarseness	10	13	0.495
	Dysphagia	7	7	0.812
	Fever	7	4	0.184
	Other	12	14	0.495

Audible breathing, even with open-mouth breathing, is characteristic of tumors large enough to cause airway obstruction. Stridor may be either inspiratory or expiratory. Hoarseness does not reliably predict vocal cord involvement or recurrent laryngeal nerve involvement. Nerve function may gradually diminish without leading to hoarseness, while some subglottic tumors may be associated with hoarseness but not vocal cord dysfunction.

The rate of progression is determined by tumor-doubling time and individual growth characteristics. Once a tracheal tumor is apparent in radiographic studies, the duration of symptoms allows the physician to consider the likely histologic type. Figure 1 provides guidance regarding the expected tumor type; individual lesions may vary in duration.

Figure 1.

Beware: there are other diseases that can mimic tracheal tumors.

Other benign and malignant causes of airway obstruction include post-intubation injury, tuberculous airway strictures (rare in North America), inflammatory stenoses related to collagen vascular disease, idiopathic laryngotracheal strictures, malignant tracheal obstruction by metastatic lymph nodes, and benign or malignant strictures of adjacent structures, larynx, or main bronchi.

A history of endotracheal intubation may indicate a related injury, and some benign lesions may mimic tumors and vice versa. If doubt remains regarding the diagnosis, endoscopy should be performed for biopsy.

How and/or why did the patient develop a tracheal tumor?

The single most common tumor of the trachea is squamous carcinoma. As in tumors in other locations of the upper and lower respiratory tract, this tumor is caused by smoking and other carcinogenic fumes. However, in contrast to carcinoma of the larynx and lung, the incidence is very low, probably because of the more laminar flow inside the trachea that allows less deposition of carcinogen. There are no known other risk factors for different tumors.

If one were to make a prognosis based on epidemiologic reviews, a “nihilistic” attitude (so termed by Licht and associates) would result since the long-term survival is dismal and surgical resection, radiation, or any other treatment appears to extend survival. The problem with epidemiologic studies is their lack of radiographic and histologic review, which is of critical importance because metastatic malignant airway obstruction is often misdiagnosed as primary tracheal tumor. Where epidemiologic surveys take these factors into account, two observations emerge: some tracheal tumors are not primary to the trachea, and surgical resection is underutilized.

The often quoted annual incidence of one primary tracheal tumor per one million inhabitants should be regarded as a rough estimate and as possibly overestimating the true incidence.

Which individuals are at greatest risk of developing a tracheal tumor?

Patients with a history of lung cancer are at greater risk of developing a second lung cancer in the trachea than are those with no such history, but tracheal tumors are so rare that special surveillance beyond oncologic follow-up cannot be recommended.

What laboratory studies should you order to help make the diagnosis, and how should you interpret the results?

There are no blood tests that predict or confirm the presence of a primary tumor with any reliability. Hemoptysis, unless it is massive, rarely leads to a perceptible decline in hemoglobin, so anemia requires careful evaluation, and metastatic disease should be ruled out. Human papilloma virus (HPV) has not been demonstrated in association with tracheal tumors.

What imaging studies will be helpful in making or excluding the diagnosis of tracheal tumor?

A chest radiograph, while not necessarily the most useful imaging study, is obtained in almost every patient with respiratory complaints. The tracheal or carinal air column may demonstrate narrowing or axial distortion.

Computed tomography (CT), particularly multidetector computed tomography (MDCT), provides detailed information about the degree of stenosis, the length of the obstruction, involvement of adjacent vascular structures, and lymphadenopathy. MDCT provides a three-dimensional reconstruction of the airway lumen and a rough estimation of tumor length, although this technique does not replace the detail of endoscopic examination; early lesions may be difficult to detect even in experienced centers, while MDCT of locally advanced tumors provides a fairly accurate measurement of axial extent. CT is useful in predicting vascular invasion, but it is unreliable in determining esophageal or submucosal tracheal invasion; the latter is commonly observed in adenoid cystic carcinoma.

The sequence of Figure 2, Figure 3, and Figure 4 show a large adenoid cystic carcinoma in a 24 year old woman. Gross tumor length may be measured by CT but the ability to perform a complete resection is difficult to predict as submucosal infiltration often extends beyond the gross mass.

Figure 2.

Figure 3.

Figure 4.

Figure 5 and Figure 6 show CT images 3 (Figure 5) and 3 1/2 (Figure 6) years after right upper lobectomy. The images demonstrate subtle progressive thickening of the left tracheal wall that was missed at the first reading of the CT. Surveillance bronchoscopy for high-grade dysplasia at the bronchial stump led to the diagnosis of squamous carcinoma shortly after the second CT. At resection, the tumor was found to be transmural with invasion of a left paratracheal lymph node.

Figure 5.

Figure 6.

What non-invasive pulmonary diagnostic studies will be helpful in making or excluding the diagnosis of a tracheal tumor?

A diagnosis of high-grade tracheal stenosis may be suspected from a deformed flow-volume loop, but lung function studies rarely provide useful information for tumor management beyond diagnosis.

What diagnostic procedures will be helpful in making or excluding the diagnosis of a tracheal tumor?

Bronchoscopy provides the precise location of the tumor and an opportunity to assess the tracheal wall above and below the main lesion. Some tumors infiltrate the airway wall in the submucosa, while others show localized polypoid growth. To determine resectability, measurement of absolute tumor length as a proportion of overall tracheal length is important.

Fiberoptic endoscopes are the instruments used most frequently. Their use requires judgment, as the endoscope may obstruct the residual lumen in large tumors. Alternatively, rigid ventilating endoscopes provide an airway during the procedure and allow endoscopic resection to be performed using the bronchoscope itself. Endoscopic lasers should be applied with great care to avoid injury to the airway above and below the tumor before surgical resection.

Is endoscopic biopsy obligatory in every tracheal tumor? If a localized lesion obstructs the tracheal lumen, chances are that tracheal resection is required for complete removal. While not every tumor must be confirmed by biopsy, long, malignant lesions and those that appear unresectable require biopsy for treatment planning.

What pathology/cytology/genetic studies will be helpful in making or excluding the diagnosis of a tracheal tumor?

Routine histologic examination of tumor biopsies with selective immunohistochemical staining provides the diagnosis. The diagnosis of salivary gland tumors and their distinction from bronchogenic carcinoma sometimes requires specialized pathologic review. While the role of genomic tumor typing has not been defined for tracheal carcinomas, it should be considered for bronchogenic carcinoma.

If you decide the patient has a tracheal tumor, how should the patient be managed?

The patient with acute airway obstruction needs immediate attention, but the long- and short-term consequences of any sudden intervention must be carefully considered. First, humidification of inspired air is provided in order to thin respiratory secretions, and efforts are made to alleviate anxiety in order to decrease oxygen consumption and ventilatory rate. Helium admixture to the inspired air (Heliox) may decrease airway resistance, in which case the oxygen fraction should be kept below 0.3.

If urgent intervention requires general anesthesia, the use of muscle relaxation should be avoided until the airway is secured. The patient’s own airway is likely to obstruct during muscle paralysis, forcing traumatic interventions that otherwise could be prevented. Endotracheal intubation in the event of clinical deterioration may be difficult, and small-bore endotracheal tubes (4, 5, and 6 mm) should be available. Awake intubation is not a suitable technique if the site and nature of the airway obstruction are unknown as it may provoke coughing and agitation; unless an experienced surgeon and anesthesiologist are at hand, general anesthesia is best avoided.

Bronchoscopic resection of luminal tumor

The purpose of bronchoscopic resection is the temporary restoration of an unobstructed airway prior to definitive therapy. Urgent tracheal resection is rarely necessary. The method of bronchoscopic resection is less important; a mechanical “coring-out” is entirely satisfactory and rarely, if ever, leads to persistent bleeding. Laser evaporation is an acceptable alternative. Endoscopic resection by definition is never complete and therefore does not replace surgical resection. Temporary relief of obstruction does not require the restoration of a normal luminal diameter, and overaggressive removal may cause injury.

Urgent radiation may diminish the tumor burden, at the price of raising the risk of resection, as radiation impairs healing of tracheal anastomoses and increases dehiscence and stricture rate. Therefore, the determination of resectability should precede radiation except in the most unusual circumstances. If a surgeon with experience in the surgical management of tracheal tumors has declared the tumor unresectable, primary radiotherapy of radiochemotherapy may be instituted.

Inhaled, oral, or parenteral steroids have no role in the management of airway obstructions that are due to tracheal tumors. If the patient has been treated with oral steroids for a clinical diagnosis of asthma, steroids should be discontinued prior to any attempt at resection.

Treatment options consist of tracheal resection with end-to-end anastomosis; primary radiation of malignant, unresectable tumors; postoperative adjuvant radiotherapy for malignant, resectable tumors; bronchoscopic resection of luminal tumor; and tracheal stenting of malignant strictures not suitable for radiotherapy.

Tracheal resection with end-to-end anastomosis

Complete resection is the best treatment for benign tumors and localized malignant tumors; long-term survival has been observed after resection of tracheal carcinomas in numerous studies. Leaving positive microscopic margins after resection of all gross disease appears to be preferable to the excessive tension that results from overly radical resection. Positive microscopic margins also are an acceptable oncologic option for long adenoid cystic carcinoma, for example.

Laryngotracheal resection of tumors in or at the subglottic space preserves laryngeal function and immediately restores airway continuity in most patients, without the need for prolonged tracheal intubation.

At the carina, resection and reconstruction with or without pulmonary resection is a technically challenging operation. The operative risk increases with descending segments of airway from laryngotracheal to carinal resection. The factor of paramount importance in the success of carinal resection is the amount of tension at the anastomosis and the extent of lung resection; surgical judgment and experience matter most.

Table 3 details the experience with primary tracheal squamous and adenoid cystic carcinoma at Massachusetts General Hospital over four decades. The resection rate rises and hospital mortality falls over time with increasing institutional experience. Modified from 15560996.