Ahn, Youngjin MD; Chang, Hyun MD; Lim, Yune Sung MD; Hah, J Hun MD; Kwon, Tack-Kyun MD, PhD; Sung, Myung-Whun MD, PhD; Kim, Kwang Hyun MD, PhD
Primary tracheal tumors are the rare subset of tumors and usually malignant in adults (80–90%)1 and benign in children (60–70%).2,3 The main presenting symptom is dyspnea, followed by other upper airway obstruction symptoms.
Reports regarding the pathologic distribution of the benign tracheal tumor are scarce and little information is available about their natural history and behavior.1 According to an epidemiologic study, relatively common benign tracheal tumors are papilloma, fibroma, and hemangioma in descending orders.4
Primary tracheal tumors account for 0.1 to 0.4% of all malignant diseases.5 The average patient age is 60 years for squamous cell carcinoma (SCC), and less than 50 years for adenoid cystic carcinomas (ACC). According to an epidemiologic study,6 59% of patients were men and 73% smoked.
Primary tracheal tumors can arise from the respiratory epithelium, salivary glands, and mesenchymal structures of the trachea. Squamous-cell carcinoma and ACC comprises about two-thirds of adult primary tracheal tumors. The remaining third are distributed widely in a heterogeneous group of malignant tumors.7
Nationwide studies were performed in some European countries.6,8–10 However, no large scale studies regarding the pathologic distribution and clinical behavior of tracheal tumors in oriental populations have been reported. In this study, we reviewed the pathologic distribution, demographic findings and factors related with the prognosis in 37 primary tracheal tumors.
MATERIALS AND METHODS
From January 1989 through December 2006, 37 patients (14 with benign tumors, 23 with malignant tumors) were diagnosed and treated at the Seoul National University Hospital. Retrospective review was performed including age, gender, initial symptom, site, tumor size, lymph node involvement, distant metastasis, histologic finding, treatment outcome, and recurrence.
Bhattacharyya’s11 staging system was adopted and used (Table 1). Survival analysis was estimated by the Kaplan-Meier method and multiple regression analysis using an SPSS version 13.0 statistical program (SPSS, Inc., Chicago).
This study was approved by the Seoul National University College of Medicine/Seoul National University Hospital Institutional Review Board.
Mean age was 21.7 years (0.3–57) for benign tumors and 52.9 years (29–69) for malignant tumors. Dividing them according to the age, all (8 of 8) childhood tracheal tumors were benign and 79.3% (23 of 29) of adult tracheal tumors were malignant. Mean follow-up duration was 56.3 months (16–205). In the same study period, 87,778 patients were diagnosed and treated for malignant tumors (4532 thoracic malignant tumors) and 37,088 patients (1211 thoracic benign tumors) were managed for benign tumors in our hospital. Malignant tracheal tumors accounted for 0.026% of all malignant disease (0.5% of all thoracic malignancies), and benign tracheal tumors comprised of 0.038% of all benign tumors (1.16% of all thoracic benign tumors).
Papilloma (3 of 14) was the most common benign tumor followed by hemangioma (2 of 14). Remainders were composed of various benign pathologies. Dyspnea was the most common presenting symptom for tracheal benign tumors. Except for the papilloma cases, which have great tendency of recurrence, tumors were managed successfully with surgical excision without recurrence. Average 11.3 number of surgeries (laser bronchoscope) were required for papilloma patients with mean interval of 200.7 days between each surgery (Table 2).
Among the 23 malignant tracheal tumors, SCCs (n = 11) and ACCs (n = 9) comprised most of the malignant tumors. SCC occurs in older age and showed male preponderance (M:F, 8:3 in SCC, 2:4 in ACC) compared with ACC (Table 3).
T stage tends to be higher in ACC compared with squamous carcinoma. Interestingly, no lymph node metastasis was observed in ACCs although SCCs showed 54.5% (6 of 11) of lymph node metastasis. Distant metastasis was discovered in two patients at the time of diagnosis (Table 4).
Five-year overall survival rate was 41.1% for SCC and 45.7% for ACC. However, no statistically significant difference (p = 0.673) was observed (Figure 1).
In SCC patients group, six patients underwent surgery, three patients received combined modality treatment and two patients received radiation therapy. Four ACC patients received surgical treatment, three patients underwent combined modality treatment and two patients received radiation therapy. Five-year disease specific survival rate for surgery, surgery and radiation, radiation only group were 50.0%, 50%, 0% for SCC patients and 50%, 100%, 50% for ACC patients respectively. However, no statistically significant survival difference was observed for both pathologies. The Bhattacharyya’s staging system was clinically relevant in our subset of patients (p = 0.016, Figure 2).
Thirteen benign tracheal tumors showed heterogenous pathologic distribution with relatively homogenous presentation. Papilloma was the most frequent one, though only 23.1% (3 of 13) of tracheal benign tumors fell into this category. Two cases of hemangioma were reported and the remaining eight were composed of various pathologies. Laser excision using rigid brochoscopy was sufficient for tumors with limited extensions. In four invasive tumors, open tracheal resection and end to end anastomosis were required. However, in papilloma cases, repetitive surgeries were required due to its extremely high recurrence tendency.
SCC was reported to be the most frequent pathology followed by ACC (Table 5).6,8–10,12–14 The prevalence of SCC in our study population was similar (47.8%, 11 of 23), however, ACC was more frequent than any other studies reported dealing with more than 50 cases of tracheal malignancy (39.1%, 9 of 23). Ethnic difference could play a role in this discrepancy, although a larger scale study is required to validate this finding.
Regarding the incidence of tracheal tumors, annual incidence was reported to be 0.6 to 3.1 among 10,000 patients in a hospital-based study in western population.5,6,8 The estimated annual incidence in our study population was 2.62 for malignant tumor and 3.78 for benign tumor (among 10,000 patients). This findings correlate well with the western studies. Unfortunately, this study was not a community based study, so we could not evaluate the annual incidence of tracheal tumor for general population.
SCC was reported to occur mainly in men in their sixth and seventh decades, whereas ACC is equally distributed between the sexes and is most common in patients in their fourth and fifth decades.7 Demographic findings in our study was similar in age (mean age, 55.2 years in SCC, 40.1 years in ACC) and sex (M:F, 8:3 in SCC, 3:6 in ACC).
There is no established staging system in American Joint Committee for Cancer guideline. Only three studies6,11,14 suggested the guideline for staging of the tracheal malignancy and only one study11 validated their result. Taking this into account, we adopted the Bhatakaryyaa’s staging system. This system was proved to be clinically relevant in our subset of patients.
Primary malignant tumors are usually treated with surgery, endoscopic resection by various techniques, and radiotherapy. Complete resection of tracheal tumors was reported to be the preferred treatment that can relieve the airway obstruction simultaneous with treating the disease.5 Surgery was also the mainstay of the treatment modality in our study (18 of 23, 78.3%). Most patients were treated with open approach and curative resection, however, endoscopic removal using laser (2 of 18, 11.15%) was successfully performed in selected early stage tumors.
Radiotherapy is indicated as an adjuvant after resection, for tumors that are unresectable or medically inoperable, and for palliation of severe symptoms.7 Adjuvant radiation therapy was performed in seven cases and primary radiation therapy was performed in unresectable cases or in patients who rejected surgical treatment (3 of 23, 2 of 23, respectively).
Pathologic distribution was reported to be related with the prognosis, and relatively higher survival was reported in ACC compared with SCC (Table 6).8,15–17 In our study population, no statistically significant survival difference was observed between SCC and ACC. Lung metastasis was the main cause of death in ACC patients (6 of 7, 85.7%). A larger scale, multi-institutional or nationwide survey is warranted to validate this survival result.
Treatment modalities clearly affect the survival. Surgery proved to be superior to radiation therapy in many studies. Five-year overall survival in surgically managed group ranged from 41 to 57%, although only 6 to 11% of 5-year overall survival was achieved in radiation group.6,8,14
In this study, we analyzed 14 benign tracheal tumors and 23 malignant tracheal tumors. Benign tumors predominated in children and composed of various pathologies although the clinical presentation was similar. SCC was most prevalent among malignant tumors and ACC was more frequently found compared with the western population. Although pathology did not affect the survival, clinical stage was considered as the significant prognostic factors. Considering the rarity of tracheal tumors, multicenter or nationwide study is warranted to validate these findings.
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