Oropharnyx

[] [] [] || nature of tumors in this area lymphatic spread is common at presentation.
 * **Epidemiolgy:** || * Oropharyngeal cancer, sometimes called throat cancer, starts in the cells that line the back of the mouth and the lower part of the throat down to the entrance to the esophagus. The part of the pharynx called the oropharynx includes the back third of the tongue, the soft part of the palate, the tonsils, and the sides and back of the throat.
 * The American Cancer Society estimated that there would be about 35,000 new cases of oral and oropharyngeal cancer every year.1
 * Although smoking and drinking (two risk factors for this cancer) are decreasing, oropharyngeal cancer is going up 3 percent every year.
 * Oropharyngeal cancers can be divided into two types, HPV-positive, which are related to human papillomavirus infection, and HPV-negative cancers, which are usually linked to alcohol or tobacco use.2 ||
 * **Etiology:** || * Oropharyngeal cancer is strongly associated with certain environmental and lifestyle risk factors, including tobacco smoking, alcohol consumption, UV light, particular chemicals used in certain workplaces.2
 * Other factors that can increase the risk of getting oropharynx cancer:
 * Long-term irritation caused by ill-fitting dentures.
 * Poor nutrition, especially a diet low in fruits and vegetables.
 * Immunosuppressive drugs.
 * Previous head and neck cancer.
 * Radiation exposure.
 * Lichen planus, a disease that often affects the cells that line the mouth. ||
 * **Signs & Symptoms:** || * A persisting sore throat.
 * Pain or difficulty with swallowing.
 * Unexplained weight loss
 * Voice changes.
 * Ear pain.
 * A lump in the back of the throat or mouth.
 * A lump in the neck.
 * A dull pain behind the sternum.
 * Cough. ||
 * **Diagnostic Procedures** 3 **:** || ** General **
 * History (alcohol intake, smoking, tobacco chewing)
 * General physical examination
 * Head and neck examination **
 * Check for palpation of the oral cavity and oropharynx
 * Mirror examination of the nasopharynx
 * Indirect laryngoscopy
 * Neck lymph node examination
 * Direct laryngoscopy
 * Biopsy of areas of interest
 * Laboratory Studies **
 * Blood counts, blood chemistry profile, urinalysis
 * Radiographic Studies **
 * Chest radiographs
 * Plain radiographs of the mandible
 * Optional positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI) or radionuclide bone scan scans
 * Malignant lymphoma studies **
 * Immunology
 * Electron microscopy
 * Special staging procedures ||
 * **Histology:** || The vast majority of tumors of the oropharynx are squamous cell carcinomas. The remainder include malignant melanomas, minor salivary gland tumors, sarcomas, plasmacytomas, lymphomas, and other rare tumors. 4
 * Malignant **
 * Squamous cell carcinoma
 * Minor Salivary Gland tumor
 * Lymphoma Sarcoma
 * Melanoma
 * Plasmacytoma
 * Other
 * Benign **
 * Papilloma
 * Retention cyst
 * Fibroma
 * Lipoma
 * Hemangioma
 * Lymphangioma
 * Neuroma
 * Other ||
 * **Lymph node drainage:** || The primary drainage of the oropharynx is to the jugulodigastric nodes located in the upper jugular chain. The tonsillar region, pharyngeal portion of the soft palate, lateral and posterior oropharangeal walls, and base of the tongue also are drained by the retropharyngeal and parapharyngeal nodes. The retropharyngeal lymph nodes are further divided into medial and lateral node chains, The parapharyngeal lymph nodes act as a junction between the spinal accessory and upper internal jugular lymphatic chains. 4
 * **Metastatic spread:** || Tumors of the base of tongue: bilateral and contra lateral lymphatic spread is common, sue to the deeply infiltrating

Tumors of the tonsillar fossa: tend to infiltrate the retromolar trigone, soft palate, and the base of tongue.

Tumors of the faucial arch: spread more superficially, may involve the hard palate or buccal mucosa. || G1= well differentiated G2= moderately differentiated G3= poorly differentiated || T2 >2 but <4 cm T3 >4 cm  T4 Invades adjacent structures T4a Invades larynx, deep/extrinsic muscle of tongue, medial ptyerygoid, hard palate, or mandible T4b Invades lateral pterygoid muscle, pterygoid plates, lateral nasopharynx, or skull base or encases carotid artery
 * **Grading:** || Tumor grading used in the oral cavity is:
 * **Staging:** || T1 2 cm or less

NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastasis N1 Metastasis in a single ipsilateral lymph node, <3 cm in greatest dimension N2 Metastasis in a single ipsilateral lymph node >3 cm but <6 cm in greatest dimension; or in multiple ipsilateral lymph nodes, none >6 cm in greatest dimension; or in bilateral or contralateral lymph nodes, none >6 cm in greatest dimension N2a Metastasis in a single ipsilateral lymph node > 3 cm but < 6 cm in greatest dimension N2b Metastasis in multiple ipsilateral lymph nodes, none >6 cm in greatest dimension N2c Metastasis in bilateral or contralateral lymph nodes, none >6 cm in greatest dimension N3 Metastasis in a lymph node >6 cm in greatest dimension Mx Presence of distant metastasis cannot be assessed M0 No distant metastasis M1 Distant meetastasis Notes: Histologic examination of a selective neck dissection specimen should include 6 or more lymph nodes. A radical or modified radical neck dissection specimen should include 10 or more lymph nodes.

Stage I T1 N0 M0 Stage IIA T2a N0 M0  Stage IIB T1 N1 M0 or T2a N1 M0 or T2b N0-1 M0  Stage III T1-2 N2 M0 or T3 N0-2 M0  Stage IVA T4 N0-2 M0  Stage IVB Any T N3 M0  Stage IVC Any T Any N M11 ||
 * **Radiation side effects:** || * Xerostomia--75% of patients. 5
 * Can be reduced with the use of IMRT
 * Mucositis and dysphagia (difficulty swallowing)
 * Laryngeal edema, fibrosis, hearing loss, and trismus
 * Osteoradionecrosis of the mandible5,6 ||
 * **Prognosis:** || Tumors arising in the oropharynx often have lymph node involvement upon detection.5

Base of tongue prognostic factors:
 * Worse prognosis than base of tongue cancers due to higher incidence of spread and size at diagnosis

Tonsillar Fossa and Faucial Arch prognostic factors:
 * Gender
 * Stage and lymph node involvement at detection
 * Decreased survival with extension into the base of tongue

Radical treatment helps get rid of disease above the clavicles, but with longer survival, occult metastatic disease becomes evident. 6
||
 * **Treatments:** || Oropharyngeal tumors are more commonly treated with radiation therapy via
 * Lateral opposed fields
 * Including the primary lesiona dna dbilateral upper cervical lymph nodes
 * Matched with an anterior field at the thyroid notch to treat the lower neck and bilateral supraclavicular lymph nodes.

Tonsil
 * T1/T3 lesions usually treated with once-daily radiation; more advanced cases treated twice daily radiation treatments
 * Large fields including adjacent structures such as:
 * Base of tongue
 * Inferior nasopharynx
 * Pharynx
 * Regional lymph nodes
 * Radiation delivered via lateral opposed fields
 * Dose ranges 74-76 Gy
 * Large fields to 45 Gy, then reduced off cord, followed with small field boost/electron boost

Base of Tongue
 * Radiation is the treatment of choice (surgery can leave malformations)
 * Large parallel opposed fields
 * Treated to 45 Gy, then reduced off cord with additional boost fields
 * Persistent tumor post radiation requires extensive resection

Lateral Pharyngeal Wall
 * Early lesions treated with radiation or surgery
 * Large tumors treated with combined-modality therapy or RT alone
 * RT fields
 * Large, including the entire pharynx
 * Fields are then reduced off cord
 * Sharp field edges are necessary in order to include the primary tumor site and the Rouviere's nodes while also shielding the spinal cord

Soft Palate and Uvula
 * Small lesuions (1cm or less) treated with either surgery alone or radiation
 * Large lesions treated with radiation followed by resection
 * Extensive lesions may include large areas, causing bilateral cervical lymph node disease
 * Radiation:
 * Treated with large lateral fields til 20 Gy, then reduced off cord, followed by intraoral cone to a total dose of 65-70 Gy

**Location of Rouviere's nodes (retropharyngeal): posterior and lateral of the pharyngeal space at C1 and C2. 5**



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 * TD 5/5 || [[file:oropharynxtd55.pdf]]

2. Oral Cancer. U.S. News & World Report. Available at: []. Accessed May 20, 2012. 3. Perez CA, Brady LA, Halpern EC, Schmidt-Ullrich RK. Principles and Practice of Radiation Oncology. 4th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2004. 4. Hoppe RT, Phillips TL, Mack III M. Leibel and Phillips Textbook of Radiation Oncology. 3rd ed. Philadelphia Pa: Elsevier Saunders; 2010. 5. Chao KS, Perez CA, Brady LW. Radiation Oncology Management Decisions. 2nd edition. Philadelphia, PA: Lippincott Williams & Wilkins. 2002. 259-274. 6 . Bentel GC. Radiation Therapy Planning. 2nd ed. The McGraw-Hill Companies; 1996: 294-295. ||
 * **References:** || 1. Oropharyngeal Cancer. Wikimedia Foundation, Inc. Available at: []. Accessed May 20, 2012.

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