General Information About Salivary Gland Cancer
Incidence and Mortality
Salivary gland tumors are a morphologically and clinically diverse group of neoplasms, which may present significant diagnostic and management challenges. These tumors are rare, with an overall incidence in the Western world of approximately 2.5 cases to 3.0 cases per 100,000 per year. Malignant salivary gland neoplasms account for more than 0.5% of all malignancies and approximately 3% to 5% of all head and neck cancers.[1,2] Most patients with malignant salivary gland tumors are in the sixth or seventh decade of life.[3,4]
Carcinogenesis and Risk Factors
Although exposure to ionizing radiation has been implicated as a cause of salivary gland cancer, the etiology of most salivary gland cancers cannot be determined.[2,3,5,6] Occupations associated with an increased risk for salivary gland cancers include rubber products manufacturing, asbestos mining, plumbing, and some types of woodworking.
Tumors of the salivary glands comprise those in the major glands (e.g., parotid, submandibular, and sublingual) and the minor glands (e.g., oral mucosa, palate, uvula, floor of mouth, posterior tongue, retromolar area and peritonsillar area, pharynx, larynx, and paranasal sinuses).[2,7] Minor salivary gland lesions are most frequently seen in the oral cavity.
Of salivary gland neoplasms, more than 50% are benign, and approximately 70% to 80% of all salivary gland neoplasms originate in the parotid gland.[1,2,8] The palate is the most common site of minor salivary gland tumors. The frequency of malignant lesions varies by site. Approximately 20% to 25% of parotid tumors, 35% to 40% of submandibular tumors, 50% of palate tumors, and more than 90% of sublingual gland tumors are malignant.[1,9]
Histologically, salivary gland tumors represent the most heterogenous group of tumors of any tissue in the body. Although almost 40 histologic types of epithelial tumors of the salivary glands exist, some are exceedingly rare and may be the subject of only a few case reports.[1,11] The most common benign major and minor salivary gland tumor is the pleomorphic adenoma, which comprises about 50% of all salivary gland tumors and 65% of parotid gland tumors. The most common malignant major and minor salivary gland tumor is the mucoepidermoid carcinoma, which comprises about 10% of all salivary gland neoplasms and approximately 35% of malignant salivary gland neoplasms.[1,12] This neoplasm occurs most often in the parotid gland.[2,12,13] This type and other histologic types of salivary gland neoplasms are reviewed in detail in the Cellular Classification of Salivary Gland Treatment section of this summary.
Most patients with benign tumors of the major or minor salivary glands present with painless swelling of the parotid, submandibular, or the sublingual glands. Neurological signs, such as numbness or weakness caused by nerve involvement, typically indicate a malignancy. Facial nerve weakness that is associated with a parotid or submandibular tumor is an ominous sign. Persistent facial pain is highly suggestive of malignancy; approximately 10% to 15% of malignant parotid neoplasms present with pain.[8,14] (Refer to the PDQ summary on Pain for more information.) The majority of parotid tumors, both benign and malignant, however, present as an asymptomatic mass in the gland.[2,8]
Early-stage low-grade malignant salivary gland tumors are usually curable by adequate surgical resection alone. The prognosis is more favorable when the tumor is in a major salivary gland; the parotid gland is most favorable, then the submandibular gland; the least favorable primary sites are the sublingual and minor salivary glands. Large bulky tumors or high-grade tumors carry a poorer prognosis and may best be treated by surgical resection combined with postoperative radiation therapy. The prognosis also depends on the following:[16,17]
- Gland in which they arise.
- Grade (i.e., degree of malignancy).
- Extent of primary tumor (i.e., the stage).
- Whether the tumor involves the facial nerve, has fixation to the skin or deep structures, or has spread to lymph nodes or distant sites.
Follow-up and Survivorship
Overall, clinical stage, particularly tumor size, may be the crucial factor to determine the outcome of salivary gland cancer and may be more important than histologic grade.
Perineural invasion can also occur, particularly in high-grade adenoid cystic carcinoma, and should be specifically identified and treated. Radiation therapy may increase the chance of local control and increase the survival of patients when adequate margins cannot be achieved.[Level of evidence: 3iiiDii] Unresectable or recurrent tumors may respond to chemotherapy.[21-23] Fast neutron-beam radiation therapy or accelerated hyperfractionated photon-beam schedules have been shown to be effective in the treatment of inoperable, unresectable, and recurrent tumors.[24-26]
Follow-up after treatment
Complications of surgical treatment for parotid neoplasms include facial nerve dysfunction and Frey syndrome also known as gustatory flushing and sweating and the auriculotemporal syndrome. Frey syndrome has been successfully treated with injections of botulinum toxin A.[27-29]
Note: Other PDQ summaries containing information related to salivary gland cancer include the following:
- Speight PM, Barrett AW: Salivary gland tumours. Oral Dis 8 (5): 229-40, 2002. [PUBMED Abstract]
- Mendenhall WM, Werning JW, Pfister DG: Treatment of head and neck cancer. In: DeVita VT Jr, Lawrence TS, Rosenberg SA: Cancer: Principles and Practice of Oncology. 9th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2011, pp 729-80.
- Ellis GL, Auclair PL: Tumors of the Salivary Glands. Washington, DC : Armed Forces Institute of Pathology, 1996. Atlas of Tumor Pathology, 3.
- Wahlberg P, Anderson H, Biörklund A, et al.: Carcinoma of the parotid and submandibular glands--a study of survival in 2465 patients. Oral Oncol 38 (7): 706-13, 2002. [PUBMED Abstract]
- Scanlon EF, Sener SF: Head and neck neoplasia following irradiation for benign conditions. Head Neck Surg 4 (2): 139-45, 1981 Nov-Dec. [PUBMED Abstract]
- van der Laan BF, Baris G, Gregor RT, et al.: Radiation-induced tumours of the head and neck. J Laryngol Otol 109 (4): 346-9, 1995. [PUBMED Abstract]
- Spiro RH, Thaler HT, Hicks WF, et al.: The importance of clinical staging of minor salivary gland carcinoma. Am J Surg 162 (4): 330-6, 1991. [PUBMED Abstract]
- Gooden E, Witterick IJ, Hacker D, et al.: Parotid gland tumours in 255 consecutive patients: Mount Sinai Hospital's quality assurance review. J Otolaryngol 31 (6): 351-4, 2002. [PUBMED Abstract]
- Theriault C, Fitzpatrick PJ: Malignant parotid tumors. Prognostic factors and optimum treatment. Am J Clin Oncol 9 (6): 510-6, 1986. [PUBMED Abstract]
- Brandwein MS, Ferlito A, Bradley PJ, et al.: Diagnosis and classification of salivary neoplasms: pathologic challenges and relevance to clinical outcomes. Acta Otolaryngol 122 (7): 758-64, 2002. [PUBMED Abstract]
- Seifert G, Sobin LH: Histological Typing of Salivary Gland Tumours. 2nd ed. Berlin, Germany: Springer-Verlag, 1991.
- Guzzo M, Andreola S, Sirizzotti G, et al.: Mucoepidermoid carcinoma of the salivary glands: clinicopathologic review of 108 patients treated at the National Cancer Institute of Milan. Ann Surg Oncol 9 (7): 688-95, 2002. [PUBMED Abstract]
- Goode RK, Auclair PL, Ellis GL: Mucoepidermoid carcinoma of the major salivary glands: clinical and histopathologic analysis of 234 cases with evaluation of grading criteria. Cancer 82 (7): 1217-24, 1998. [PUBMED Abstract]
- Spiro RH, Huvos AG, Strong EW: Cancer of the parotid gland. A clinicopathologic study of 288 primary cases. Am J Surg 130 (4): 452-9, 1975. [PUBMED Abstract]
- Parsons JT, Mendenhall WM, Stringer SP, et al.: Management of minor salivary gland carcinomas. Int J Radiat Oncol Biol Phys 35 (3): 443-54, 1996. [PUBMED Abstract]
- Vander Poorten VL, Balm AJ, Hilgers FJ, et al.: The development of a prognostic score for patients with parotid carcinoma. Cancer 85 (9): 2057-67, 1999. [PUBMED Abstract]
- Terhaard CH, Lubsen H, Van der Tweel I, et al.: Salivary gland carcinoma: independent prognostic factors for locoregional control, distant metastases, and overall survival: results of the Dutch head and neck oncology cooperative group. Head Neck 26 (8): 681-92; discussion 692-3, 2004. [PUBMED Abstract]
- Spiro RH: Factors affecting survival in salivary gland cancers. In: McGurk M, Renehan AG, eds.: Controversies in the Management of Salivary Gland Disease. Oxford, UK: Oxford University Press, 2001, pp 143-50.
- Gormley WB, Sekhar LN, Wright DC, et al.: Management and long-term outcome of adenoid cystic carcinoma with intracranial extension: a neurosurgical perspective. Neurosurgery 38 (6): 1105-12; discussion 1112-3, 1996. [PUBMED Abstract]
- Hosokawa Y, Shirato H, Kagei K, et al.: Role of radiotherapy for mucoepidermoid carcinoma of salivary gland. Oral Oncol 35 (1): 105-11, 1999. [PUBMED Abstract]
- Borthne A, Kjellevold K, Kaalhus O, et al.: Salivary gland malignant neoplasms: treatment and prognosis. Int J Radiat Oncol Biol Phys 12 (5): 747-54, 1986. [PUBMED Abstract]
- Spiro RH: Salivary neoplasms: overview of a 35-year experience with 2,807 patients. Head Neck Surg 8 (3): 177-84, 1986 Jan-Feb. [PUBMED Abstract]
- Licitra L, Cavina R, Grandi C, et al.: Cisplatin, doxorubicin and cyclophosphamide in advanced salivary gland carcinoma. A phase II trial of 22 patients. Ann Oncol 7 (6): 640-2, 1996. [PUBMED Abstract]
- Wang CC, Goodman M: Photon irradiation of unresectable carcinomas of salivary glands. Int J Radiat Oncol Biol Phys 21 (3): 569-76, 1991. [PUBMED Abstract]
- Buchholz TA, Laramore GE, Griffin BR, et al.: The role of fast neutron radiation therapy in the management of advanced salivary gland malignant neoplasms. Cancer 69 (11): 2779-88, 1992. [PUBMED Abstract]
- Krüll A, Schwarz R, Engenhart R, et al.: European results in neutron therapy of malignant salivary gland tumors. Bull Cancer Radiother 83 (Suppl): 125-9s, 1996. [PUBMED Abstract]
- Naumann M, Zellner M, Toyka KV, et al.: Treatment of gustatory sweating with botulinum toxin. Ann Neurol 42 (6): 973-5, 1997. [PUBMED Abstract]
- Arad-Cohen A, Blitzer A: Botulinum toxin treatment for symptomatic Frey's syndrome. Otolaryngol Head Neck Surg 122 (2): 237-40, 2000. [PUBMED Abstract]
- von Lindern JJ, Niederhagen B, Bergé S, et al.: Frey syndrome: treatment with type A botulinum toxin. Cancer 89 (8): 1659-63, 2000. [PUBMED Abstract]