Abstract
Purpose
To evaluate surgical outcomes for adenoid cystic carcinoma (ACC) of the external auditory canal (EAC).
Methods
Forty-three patients with ACC of the EAC in Eye and ENT Hospital of Fudan University were analyzed retrospectively for survival. The patients were staged according to the modified Pittsburgh staging system. Thirteen patients with T1 stage underwent local resection (LR), 6 patients with T1 stage underwent lateral temporal bone resection (LTBR), and 8 patients with T1 stage underwent LTBR including superficial parotidectomy (SP). Two patients with T2 stage underwent LTBR, and 1 patient with T2 stage underwent LTBR + SP. Three patients with T3 stage underwent LTBR. One patient with T4 stage underwent LTBR, two patients with T4 stage underwent subtotal temporal bone resection (STBR), and 7 patients with T4 stage underwent LTBR + SP.
Results
Of all patients that underwent surgery, 13 died of their primary cancers during the follow-up time. The 5-year survival rates of patients with T stages 1 through 4 were 85%, 67%, 67%, and 30%, respectively. There was statistically significant difference in 5-year survival rate between T1 and other stages (T2, T3, T4) using the log-rank test ( p < 0.05). There was significant difference in 5-year survival rate between T4 and other stages using the log-rank test ( p < 0.05). The 5-year survival rates after LR, LTBR or LTBR plus SP for T1 were 77%, 87% and 100%, respectively. The 5-year survival rates after LTBR, STBR or LTBR plus SP for T4 were 0%, 50% and 29%, respectively. The 5-year survival rates for 19 patients with clear surgical margins and 24 patients with positive margins were 89% and 54%, respectively. The 5-year survival rates of patients with radiotherapy and without radiotherapy were 62% and 86%, respectively.
Conclusion
An en bloc resection including superficial parotidectomy is favored in an effort to produce negative surgical margins for ACC of the EAC. Adjunctive radiotherapy is used for patients with positive margins and in advanced lesions.
1
Introduction
Adenoid cystic carcinoma (ACC) of the external auditory canal (EAC) is an extremely rare tumor originating from the salivary gland of the head and neck, which accounts for 5%–20% of the primary malignancies of the EAC and 4%–11% of the salivary gland neoplasms . ACC of the EAC mainly present with otalgia and mass in the ear. Diagnosis is usually delayed due to the early uncharacteristic symptoms and the slow growth of the tumor. Because of the rarity of the ACC, it is poorly experienced for an individual or single institution in formulating an optimal treatment strategy. Arriaga et al. from the University of Pittsburgh established a staging system for squamous cell carcinoma of the external auditory canal in 1990, with minimal revision by Moody et al. in 2000. The lack of an accurate and internationally accepted staging system for ACC of the EAC impedes helpful selection of the surgical approaches and meaningful evaluation of the different investigators.
ACC of the EAC is associated with a high risk of local recurrence and significant distant metastasis, mainly to the lungs, from surgical management many years later. Local resection can be performed when the tumor is limited to the soft tissue of the external auditory canal. For extended tumor, however, a lateral temporal bone resection is needed. Because of the proximity of the area to the lateral skull base and the major neurovascular structures, a total temporal bone resection of the malignancy is quite difficult. Kinney et al. concluded that a piecemeal lateral temporal bone resection of all gross tumor followed by radiotherapy gave comparable results .
The present report evaluates our experience with survival outcomes for 43 cases of ACC of the EAC that underwent surgery between 1992 and 2008.
2
Materials and methods
2.1
General data
Approval was obtained from the Institutional Internal Review Board. A retrospective survey was performed on 43 patients of ACC of the EAC who underwent surgery at the Eye and ENT Hospital of Fudan University. Twenty-four patients were men, and 19 patients were women. The patients ranged in age from 21 to 74 years, and the average age at the time of surgery was 51 years.
2.2
Clinical manifestations
Twenty and 18 of 43 patients of ACC of the EAC presented a history of mass and otalgia, respectively. The rates of occurrence of clinical symptoms and signs are listed in Table 1 .
| Symptoms and signs | Cases (n) | Percentage (%) |
|---|---|---|
| Mass in the EAC | 20 | 47 |
| Otalgia | 18 | 41 |
| Hearing loss | 6 | 14 |
| Otorrhea | 4 | 9 |
| Facial palsy | 0 | 0 |
2.3
Clinical stage
Presently, there is no established Union Internationale Contre le Cancer TNM staging system for ACC of the EAC. The most commonly used staging system was derived from a series of articles for squamous cell carcinoma of the EAC from the University of Pittsburgh . In our current study, the staging system applied was that recommended by Moody et al. of the University of Pittsburgh, although there may be some potential differences. T1, tumor limited to the external auditory canal without bony erosion or evidence of soft tissue involvement; T2, tumor with limited external auditory canal bone erosion (not full thickness) or limited (< 0.5 cm) soft tissue involvement; T3, tumor eroding the osseous external auditory canal (full thickness) with limited (< 0.5 cm) soft tissue involvement or tumor involving the middle ear and/or mastoid; T4, tumor eroding the cochlea, petrous apex, medial wall of the middle ear, carotid canal, jugular foramen, or dura or with extensive soft tissue involvement (> 0.5 cm), such as involvement of temporomandibular joint or styloid process, or evidence of facial paresis. According to the modified Pittsburgh tumor–lymph node–metastasis staging system, in total, there were 27 T1, 3 T2, 3 T3, and 10 T4 ACCs of the EAC in our data ( Table 2 ), which corresponded to 27 Stage 1 (T1N0M0), 3 Stage 2 (T2N0M0), 3 Stage 3 (T3N0M0), and 10 Stage 4 (T4N0M0/T4N1M0) tumors. So we state the T classification as a clinical stage at presentation here.
| TNM staging | Cases (n) | Percentage (%) |
|---|---|---|
| Size of tumor (T) | ||
| T1 | 27 | 63 |
| T2 | 3 | 7 |
| T3 | 3 | 7 |
| T4 | 10 | 23 |
| Lymph node metastasis (N) | ||
| N0 | 42 | 98 |
| N | 1 | 2 |
| Distant metastasis (M) | ||
| M0 | 43 | 100 |
| M | 0 | 0 |
| Clinical stage | ||
| I | 27 | 63 |
| II | 3 | 7 |
| III | 3 | 7 |
| IV | 10 | 23 |
2.4
Surgical approaches
The objective was en bloc excision with clear margins. The standard surgical protocol was displayed in Table 3 . Our surgical technique allowed for a resection to the same specimen and anatomic boundaries as the classically described local resection (LR), lateral temporal bone resection (LTBR), and subtotal temporal bone resection (STBR).There were 13 cases of LR, 12 cases of LTBR, 2 cases of STBR, and 16 cases of LTBR including superficial parotidectomy (SP) in all ACCs of the EAC. The surgical approaches related to clinical TNM staging are displayed in Table 4 .
| Surgery | Specimen resected | Boundaries (Limits of resection) |
|---|---|---|
| LR | Skin of external auditory canal | Tympanic membrane intact |
| LTBR | En bloc removal of external auditory canal, tympanic membrane, malleus and incus Optional: parotid, mandibular condyle, infratemporal fossa or neck dissection | Medial: stapes, facial nerve Posterior: mastoid cavity Superior: epitympanum Anterior: temporomandibular joint Inferior: jugular bulb |
| STBR | LTBR plus otic capsule Optional: facial nerve, superior and posterior dura or sigmoid sinus | Neurovascular structures of jugular foramen and carotid canal |
| Stage | LR | LTBR | STBR | LTBR + SP |
|---|---|---|---|---|
| T1 (n = 27) | 13 | 6 | 0 | 8 |
| T2 (n = 3) | 0 | 2 | 0 | 1 |
| T3 (n = 3) | 0 | 3 | 0 | 0 |
| T4 (n = 10) | 0 | 1 | 2 | 7 |
2.5
Radiotherapy
All 43 patients of ACC of the EAC were treated surgically, 29 patients received surgery with adjuvant radiotherapy (50-60 Gy), and 14 patients with T1 cancers received surgery alone.
2.6
Statistical analysis
Statistical analysis was performed with the SPSS software package (Chicago, IL, USA). Survival analysis was performed with the Kaplan–Meier method. The survival rates were compared by the log-rank test between groups of patients.
2
Materials and methods
2.1
General data
Approval was obtained from the Institutional Internal Review Board. A retrospective survey was performed on 43 patients of ACC of the EAC who underwent surgery at the Eye and ENT Hospital of Fudan University. Twenty-four patients were men, and 19 patients were women. The patients ranged in age from 21 to 74 years, and the average age at the time of surgery was 51 years.
2.2
Clinical manifestations
Twenty and 18 of 43 patients of ACC of the EAC presented a history of mass and otalgia, respectively. The rates of occurrence of clinical symptoms and signs are listed in Table 1 .
