Salivary+Gland

Parotid, Submandibular, Sublingual, and many dispersed minor salivary glands Pleomorphic adenoma:
 * **Epidemiolgy:** || * The parotid gland is the site with the highest incidence of salivary gland tumors (85%)1
 * About 25% with malignant parotid tumors present with lymph node involvement
 * The submandibular gland is involved in about 10% of all instances.1
 * Up to 33% of tumors that arise in the submandibular gland invade the lower jaw
 * High grade salivary tumors have a high risk of lymph node metastasis1
 * Especially epidermoid
 * Tumors of the salivary gland are rare and make up only 4-7% of all cancers of the head and neck region.1
 * Tumors of the minor salivary gland account for 2-3% of all head and neck cancers, about 75% are malignant.1 ||
 * **Etiology:** || * Most major and minor salivary cancers are of unknown origin and etiologic factors are poorly understood.1
 * Low-dose ionizing radiation in childhood may account for some cases of malignant salivary gland tumors.1
 * Possible risk factors such as dental radiographs may be correlated with the incidence of salivary gland tumors. 1
 * Minor salivary gland adenocarcinomas have ben linked to exposure to hardwood dust.1
 * Gender seems to not impact incidence.1 ||
 * **Signs & Symptoms:** || Salivary Glands: 2
 * Present with painless, fast growing mass that may have been present in the past without being detected
 * Although around 25% of those with parotid tumors may have nerve involvement of the face, only 10% have complaints of pain
 * Pain may also be likely with tumors involving deeper structures.
 * Symptoms suggestive of a malignant salivary gland tumor are fast growth rate, pain, facial nerve palsy, childhood occurence, skin involvement, and cervical adenopathy. ||
 * **Diagnostic Procedures:** || * Patient history and physical exam with much importance placed on the palpation of the head and neck
 * Computed Tomography scans can reveal the extent of the disease
 * Magnetic resonance is used to help distinguish between tissues
 * Salivary gland malignancies, which have been known to be very heterogeneous, are biopsied with an open technique, and upon confirmation are surgically
 * removed.5 ||
 * **Histology:** || There are several histologic classifications of malignant salivary gland tumors:
 * mixed tumors arise from existing benign tumors, which can be aggressive and present with regional lymph node metastasis.

Adenoid cystic carcinoma
 * Solid-type/high-grade tumors often have perineural invasion in 50% of cases.

Mucoepidermoid carcinoma
 * Typically arise within the minor salivary glands and present with lymph node metastasis.
 * Low-grade tumors are slow growing and rarely invade regional or local structures.
 * High-grade tumors are locally aggressive which commonly metastasize to regional lymph nodes.

Adenocarcinoma (NOS)
 * High-grade often with lymph node metastasis, lung metastasis and bone metastasis.
 * Low-grade tumors behave less aggressively and often arise from the minor salivary glands.
 * Most common ex pleomorphic adenoma.

Acinic cell carcinoma
 * Typically low-grade slow growing tumors that arise from the parotid gland. These tumors may invade bone, blood vessels, nerves and the skin.
 * Undifferentiated Acinic cell carcinomas are widely invasive and metastasize early, as they are highly malignant.

Squamous cell carcinoma Submandibular glands: The lymphatics of the mandibular gland include: the submandibular, subdigastric, and high and middle jugular lymph nodes. Sublinguinal glands: The sublinguinal glands drains either to the submandibular lymph nodes or, more posteriorly, into the deep internal jagular chain.5
 * High-grade aggressive tumors, which present with deep fixation and facial nerve palsy.6 ||
 * **Lymph node drainage:** || Parotid glands: The parotid gland lymphatics include: the subparotid, paraparotid, tail of parotid, submandibular, upper jugular, subdigastric, middle & lower jugular and posterior triangle lymph nodes.

|| In most instances, the histologic type defines the grade (i.e., salivary duct carcinoma is high grade; basal cell adenocarcinoma is low grade). 4 ||
 * **Metastatic spread:** || * Most salvary gland tumors are benign.
 * The most common histology is pleomorphic adenoma, which is characterized by slow growth and few symptoms, and is most frequently seen in the parotid gland. 3
 * Signs of malignant disease include persistent pain, numbness, and facial nerve weakness. 3
 * Metastatic spread is most frequently to the lungs. 4 ||
 * **Grading:** || Histologic grading is applicable only to certain types of salivary cancer: mucoepidermoid carcinoma, adenocarcinoma not otherwise specified, or when either of these is the carcinomatous element of carcinoma in pleomorphic adenoma. 4
 * **Staging:** || ** Salivary Gland Staging ** 4


 * Primary Tumor (T) **

All categories may be subdivided: (a) solitary tumor, (b) multifocal tumor (the largest determines the classification).

TX - Primary tumor cannot be assessed T0 - No evidence of primary tumor T1 - Tumor 2 cm or less in greatest dimension without extraparenchymal extension T2 - Tumor more than 2 cm but not more than 4 cm in greatest dimension without extraparenchymal extension T3 - Tumor more than 4 cm and/or tumor having extraparenchymal extension T4a - Tumor invades skin, mandible, ear canal, and/or facial nerve T4b - Tumor invades skull base and/or pterygoid plates and/or encases carotid artery


 * Regional Lymph Nodes (N) **

NX - Regional lymph nodes cannot be assessed N0 - No regional lymph node metastasis N1 - Metastasis in a single ipsilateral lymph node, 3 cm or less in greatest dimension N2 - Metastasis in a single ipsilateral lymph node, more than 3 cm but not more than 6 cm in greatest dimension, or in multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension, or in bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension N2a - Metastasis in a single ipsilateral lymph node, more than 3 cm but not more than 6 cm in greatest dimension N2b - Metastasis in multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension N2c - Metastasis in bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension N3 - Metastasis in a lymph node, more than 6 cm in greatest dimension


 * Distant Metastasis (M) **

MX - Distant metastasis cannot be assessed M0 - No distant metastasis M1 - Distant metastasis


 * Stage Grouping **

Stage I - T1 N0 M0

Stage II - T2 N0 M0

Stage III - T3 N0 M0

T1 N1 M0

T2 N1 M0

T3 N1 M0

Stage IVA - T4a N0 M0

T4a N1 M0

T1 N2 M0

T2 N2 M0

T3 N2 M0

T4a N2 M0

Stage IVB - T4b Any N M0 Any T N3 M0

Stage IVC - Any T Any N M1 || Submandibular gland- the field should include the entire ipsilateral neck and submandibular area should be irradiated.2 ||
 * **Radiation side effects:** || Xerostoma or decrease salivary function is the major side effect specific to the salivary glands. Sparing the contralateral gland can help prevent this from happening. ||
 * **Prognosis:** || Outlook is largely affected by tumor grade, postsurgical residual disease, tumor size, facial nerve invasion, and presence of positive cervical nodes.2 ||
 * **Treatments:** || Parotid gland- two main treatment types include a unilateral anterior and posterior wedge pair, utilizing 4-6 MV. This type of treatment can reduce exit dose through the contralateral eye. The second of the two and more common consists of homolateral fields of 12-16MeV. The electrons are used either alone or in conjunction with photons. Newer treatment types such as IMRT and IGRT have become common treatment types.2
 * **TD 5/5:** || TD 5/5 for the salivary glands is 32Gy.2 ||
 * **References:** || # Washington CM., Leaver D. //Principles and Practice of Radiation Therapy//. 3rd ed. Mosby, Inc; 2010: 712-713.
 * 1) Chao KS, Perez CA, Brady LW. //Radiation Oncology Management Decisions//. 3rd edition. Philadelphia,PA: Lippincott, Williams & Watkins. 2011. 237-245.
 * 2) Abraham J, Allegra CJ, Gulley J. //Bethesda Handbook of Clinical Oncology//. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.
 * 3) American Joint Committee on Cancer. //AJCC Cancer Staging Manual//. 6th ed. New York, NY: Springer; 2002.
 * 4) Chao KSC, Perez CA, Brady LW. //Radiation Oncology Management Decisions//. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2002: 213-222.
 * 5) Wong W. MR Imaging of the Lower Face and Salivary Glands. Available at []. Accessed May 27, 2012 . ||

Back to Week 2