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For malignant growths of the minor salivary glands, wide local excision is recommended. This approach may be extensive, even including a skull base resection, depending on the location, size, and extension of the tumor. Tumors involving the maxillary sinus and nasal cavity may require partial or total maxillectomy. If the ethmoid is involved with extrasinus extension, craniofacial resection, orbital exenteration, or both may be required for more extensive tumors. A transoral or combined transoral–transcervical approach is used for malignant neoplasms of the minor salivary glands that affect the oral cavity and oropharynx. A partial or total laryngectomy or even tracheal resection is required for minor salivary gland tumors involving the larynx or trachea.
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Neck dissection is the recommended treatment of the neck for malignant salivary gland tumors (1) with clinically apparent cervical adenopathy (14% of cases), (2) for tumors >4 cm (in which the risk of occult metastases is >20%), or (3) for a high-grade histology (in which the risk of occult metastases is >40%) (Table 19–5). Elective neck dissection for adenoid cystic carcinoma generally is not recommended because the risk of occult nodal metastasis is low.
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Both conventional and neutron-beam radiation therapy have been advocated as single-modality treatments for T1 and T2 malignant salivary gland neoplasms. This approach is controversial, but may be considered if there are real contraindications to surgery.
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Adjuvant radiation to the tumor resection bed improves local control for (1) T3 and T4 tumors; (2) tumors of high-grade histology (see Table 19–4); (3) positive nodes or perilymphatic invasion; (4) facial or other perineural involvement; (5) a close or positive surgical margin; (6) bone, cartilage, or muscle invasion; or (7) recurrent disease. The standard radiation therapy used is a unilateral mixed electron and photon technique. Postoperative radiation to the neck is recommended, as above, for major and certain minor salivary gland primary sites when there are positive neck nodes. Radiation is an acceptable alternative for a node-negative (ie, N0) neck with aggressive features (see indications for neck dissection). For minor salivary gland tumors, elective radiation of the N0 neck is advocated only for primary tumors of the tongue, floor of mouth, pharynx, and larynx. Conventional radiation has been shown to have prohibitively poor local control rates for inoperable disease.
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Neutron-beam radiation has been shown to be more effective than conventional radiation against malignant salivary gland disorders; it results in a higher degree of tumor destruction with fewer toxic effects to surrounding normal tissues. In particular, neutron-beam radiation protocols have been more successful than conventional radiation in treating adenoid cystic carcinoma. Neutron-beam therapy can achieve excellent locoregional control, higher than mixed beam and photons in advanced, recurrent, as well as incompletely resected salivary neoplasms. It is also the preferred treatment for inoperable disease. Fast neutron therapy is not widely available.
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The role for chemotherapy in the treatment of malignant salivary gland disorders is limited to the palliative setting, such as in advanced-stage or metastatic disease not amenable to local therapies including surgery and/or radiation. Partial or complete responses have been achieved in up to 50% of patients, which typically last 5–8 months and may include significant pain control. Most of these patients have adenoid cystic carcinoma, mucoepidermoid carcinoma, or high-grade adenocarcinoma. Currently, paclitaxel is the agent used most frequently. Although chemotherapy alone does not improve survival rates, the integration of radiation and chemotherapy has been shown to increase local control and represents an improvement in the management of salivary gland malignancies.
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Molecular Targeted Therapy
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Recent studies suggest new molecular agents as potential alternatives to current chemotherapeutic agents in the treatment of salivary gland malignancies. They may be preferred over chemotherapy due to fewer side effects and potentially greater efficacy. Novel agents targeting specific receptors, such as epidermal growth factor receptor (EGFR) and Her-2/neu, have shown promising results in their future additions to the treatment regimens for salivary gland cancers.
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Treatment of Recurrence and Metastatic Disease
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Recurrent, malignant salivary gland tumors are treated with the same guidelines as for primary disease. Neutron-beam radiation can, in selected cases, be used when previous external beam radiation has already been administered. In patients with metastatic disease, a “wait-and-watch” policy is advocated, and systemic treatment is currently reserved for patients with symptomatic or progressive disease. The role of molecular targeted agents in these tumors remains investigational.
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Complications of Treatment
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The complications of the treatment of salivary gland tumors include complications of surgery and those of radiation therapy.
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Complications Related to Surgery
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Facial nerve (or other nerve) paralysis, hematoma, salivary fistula or sialocele, Frey syndrome, and cosmetic deformity are among the surgical complications.
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Complications Related to Radiation Therapy
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Complications of radiation include acute mucositis, trismus and fibrosis, osteoradionecrosis, and impairment of vision. Since most radiation protocols for malignant salivary gland neoplasms involve unilateral treatment, xerostomia occurs less often than in the treatment of other upper aerodigestive tract tumors.
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Hematol Oncol Clin North Am 2008;22(6):1279
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Prott FJ, Micke O, Haverkamp U et al. Results of fast neutron therapy of adenoid cystic carcinoma of the salivary glands.
Anticancer Res 2000;20(5C):3743
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Spiro JD, Spiro RH. Cancer of the parotid gland: role of 7th nerve preservation.
World J Surg 2003;27(7):863
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