Squamous cell carcinoma of the parotid gland: A population-based analysis of 2545 cases




Abstract


Purpose


Squamous cell carcinoma (SCC) of the parotid gland is an uncommon tumor, which generally affects older patients. In this study, we explore various aspects of this entity using a national population-based database.


Methods


The Surveillance, Epidemiology, and End Results (SEER) registry was used to extract data on frequency, incidence, and disease-specific survival (DSS) from 1973 to 2009. Variables analyzed included age, gender, race, histologic grade, stage and treatment. Cox proportional hazards analysis was conducted.


Results


A total of 2545 cases were identified. Parotid SCC was most common in males (79.8%), whites (92.9%), and patients aged ≥ 75 years (51.4%). Incidence increased slightly over the past three decades (annual percent change 1.90%, p < 0.05). Overall 5-year DSS was 54.4%. Statistically significant poor prognostic factors included black race, age ≥ 75 years, tumor T3 or greater, and higher clinical stage at diagnosis. Elective neck dissection (END) in patients staged N0 was associated with higher DSS (78.3% versus 51.1%, p < 0.0001). The omission of END was associated with a three-fold greater hazard of death (hazard ratio 3.19, 95% confidence interval 1.53–7.26, p = 0.0016), regardless of whether or not radiotherapy was given.


Conclusion


Parotid SCC is uncommon, and data on treatment decisions are limited. Our study profiles the demographic, clinicopathologic, incidence, and survival features of this entity. Perhaps most notably, our results support the practice of END of the N0 neck.



Introduction


Salivary gland neoplasms are relatively uncommon, with an overall incidence of 2.5 to 3 cases per 100,000 persons in the Western world . The majority of these lesions (approximately 70%–80%) originate in the parotid gland . Malignant salivary gland tumors are considerably less common; they account for approximately 3% to 5% of all head and neck cancers and have a tendency to present in the sixth or seventh decades of life . Squamous cell carcinoma (SCC) originating in the parotid gland is a rare, often aggressive malignancy which makes up 0.1% to 3.4% of all parotid malignancies . Given its rarity, epidemiologic data and data on the management of primary parotid SCC are limited.


Although surgical resection is the principal treatment modality for primary parotid gland malignancies, several factors influence management decisions, among them tumor size, extent, facial nerve function, and the presence of metastatic disease . One particular area of interest concerns the management of the regional lymphatics. The indications for therapeutic neck dissection in the presence of regional metastasis are relatively well defined; however, although most experts recommend elective neck dissection (END) in the management of the clinically negative (N0) neck, evidence regarding its impact on survival is limited . Occult metastases are reported in 12% to 48% of patients with all forms of parotid gland carcinoma; nevertheless, data describing the impact of elective neck treatment (neck dissection or radiotherapy) on survival are rather limited .


In the present study, we use a national population-based database to investigate the demographic, clinicopathologic, incidence, and survival and prognostic features of primary SCC of the parotid gland. In addition, we aim to examine the role of neck dissection in the treatment of patients without clinically evident neck disease. To our knowledge, our study represents the largest population-based series of primary parotid SCC to date.

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Aug 24, 2017 | Posted by in OTOLARYNGOLOGY | Comments Off on Squamous cell carcinoma of the parotid gland: A population-based analysis of 2545 cases

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