Oropharynx

Men are affected more than women with a ratio of 4:1 Tonsillar cancer is the most common primary site in the oropharynx. 95% of tonsillar cancers are SCC with the remaining being mostly lymphomas. 5 ||  Lung is the most common site. 7 Oropharyngeal Carcinoma has a high likelyhood for cervical node involvement. 60%-80% of the time, base of tongue tumor may have palpable nodes at the time of diagnosis. Even when the neck is clinially negative, the incidence of occult metastatic disease is approsimately 20%. Bilateral neck disease at the time of diagnosis is approximately 40%. Tonsillar lesions have palpable metastatic neck nodes at diagnosis in 60%-70% of cases while pharyngeal wall lesions are approximately 50%-60% and soft palate in 40% to 50%. The nodes most commonly involved are the jugulodigastric (Level II). 5 || G1: well-differentiated. G2: moderately well-differentiated. G3: poorly-differentiated. G4: undifferentiated. 8 || TX - Primary tumor cannot be assessed T0 - No evidence of primary tumor Tis - Carcinoma in situ T1 - Tumor greater or equal to 2 cm in greatest dimension T2 - Tumor is greater then 2 cm but not greater then 4 cm in greatest dimension T3 - Tumor greater then 4 cm in greatest dimension T4 - Tumor invades adjacent structures [e.g., pterygoid muscle(s), mandible, hard palate, deep muscle of tongue, larynx]
 * ​ Epidemiology: || The median age affected is in the range of 55-65 years.
 * Etiology: || Heavy alcohol consumption and smoking are two big factors for this patient population. In addition, patients who survive their first cancer of the oropharynx, have high associated incidence of second primary tumors of the upper aerodigestive tract. 5   ||
 * Signs & Symptoms: || Characteristic symptoms of oropharynx cancer include: unexplained weight loss, local pain,change in voice, dysphagia, referred otalgia (earache), enlarged lymph node , and sometimes airway distress . 6  Trismus (lockjaw) can also be a late manifestation. 1 ||
 * Diagnostic Procedures: || A patient should undergo a thorough physical examination. The exam should include palpation of nodal regions and visualization of entire oral cavity. A direct and indirect laryngoscopy is used to look for abnormalities . A biopsy of any suspicious lesion should be performed. Routine diagnostic studies include CT or MRI of the head and neck and a Chest x-ray. 6 <span style="color: #0000ff; font-family: Georgia,serif;"> Radiographs of the neck and mandible are essential in the pretreatment workup. Laboratory studies include: CBC, blood chemistry and urinalysis. <span style="color: #0000ff; font-family: 'Times New Roman',Times,serif; font-size: 80%; vertical-align: super;">1 ||
 * Histology: || <span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 110%;"> Many oropharyngeal carcinomas are keratinizing squamous cell carcinomas which can be graded I-IV depending on the degree of differentiation. Carcinomas arising in the faucial arch tend to be keratinizing and are more differentiated than those of the tonsillar fossa. Lymphoepitheliomas are less common in tonsil than nasopharynx. Malignant lymphomas, like non-Hodgkin's type, constitute for 10-15% of malignant tonsilar tumors. Salavary gland type is uncommon in the tonsil or faucial arch. <span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 80%; vertical-align: super;">2  ||
 * Lymph Node Drainage: || <span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 110%;">The tonsillar fossa and faucial arch have a rich, submucosal lymphatic network that is laterally grouped with four to six lymphatic ducts. These ducts drain into the subdigastric, upper cervical, and parapharyngeal lymph nodes. Submaxillary lymph nodes may be involved with lesions of the retromolar trigone, buccal mucosa, and base of tongue.<span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 80%; vertical-align: super;">2 ||
 * Metastatic Spread: || Hematogenous metastatis is related with tonsillar and base of tongue primaries.
 * Grading: || Tumor grading is recommended using Broder classification (Tumor Grade [G]):
 * Staging: || The American Joint Committee on Cancer staging classification for carcinoma of the oropharynx uses the TNM staging system.
 * __Primary tumor (T)__**

NX - Regional lymph nodes cannot be assessed N0 - No regional lymph node metastasis N1 - Metastasis in a single ipsilateral lymph node, less then or equal to 3 cm in greatest dimension N2 - Metastasis in a single ipsilateral lymph nodes, greater then 3 cm but not greater then 6 cm in greatest dimension, or in multiple ipsilateral lymph nodes, none greater then 6 cm in greatest dimension, or in bilateral or contralateral lymph nodes, none greater then 6 cm in greatest dimension N2a - Metastasis in a single ipsilateral lymph node greater then 3 cm but none greater then 6 cm in greatest dimension N2b- Metastasis in multiple ipsilateral lymph nodes, none greater then 6 cm in greatest dimension N2c - Metastasis in bilateral or contralateral lymph nodes, none greater then 6 cm in greatest dimension N3 - Metastasis in a lymph node greater then 6 cm in greatest dimension
 * __Regional lymph nodes (N)__**

MX - Distant metastasis cannot be assessed M0 - No distant metastasis M1 - Distant metastasis 3 || ​Xerostomia - ( moderate to severe) occurs in approximately 75% of patients treated with conventional beam arrangement but can decrease with the use of IMRT. ​Mucositis and Dyspahgia - are the most common acute irradiation side effect. Usually occurs at around 3000 cGy for conventional fractionation scheme. Laryngeal edema, fibrosis, hearing loss, and trismus occasionally occur. Necrosis of mandible depends on the state of tumor, irradiation dose delivered to the mandible, use of prophylactic dental care, trauma (including dental extractions), and irradiation technique, and is approximately 6% when the tumor is over or adjacent to the mandible and 0% when it is not. Can occur at around 5000-6000 cGy for a conventional fractionation scheme. Carotid artery rupture - occures in up to 3% of patients treated with surgery for irradiation failure.
 * __Distant metastasis (M)__**
 * Radiation Side Effects: || **__ Tonsillar Fossa and Faucial Arch __**

Xerostomia - (moderate to severe) occurs in approximately 75% of patients treated with conventional beam arrangement. IMRT can significantly reduce this complication exponentially, at 4% per Gy of parotid mean dose. 3,4 || Stage of primary tumor and the presence of cervical nodes has a significant correlation with 5-yr survival rates. Decreased survival is associated with tumor extension into the base of the tongue. Whether or not one is older or younger than 40 has had no effect on survival in some studies completed.
 * __Base of Tongue__**
 * Prognosis: || <span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 90%;"><span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 120%;">Tonsillar Fossa and Faucial Arch:

Base of Tongue: These cancers have a worse prognosis than those in the oral tongue because of their greater size at the time of diagnosis, the more common spread to adjacent structures, and the increased rate of lymphatic spread. They may have a prognosis close to oral tongue cancers when they are looked at stage for stage.¹ <span style="color: #298000; font-family: 'Comic Sans MS',cursive;">

<span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 120%;">Overall 5-year survival depends on the site and stage of the tumor but the range is 30%-60%. Tonsil and soft tissue lesions have the best prognosis while pharyngeal wall and base of tongue have a very serious outlook. Mortality in oropharyngeal cancers is from regionally recurrent or uncontrollable disease. Radical treatment helps get rid of disease above the clavicles, but with longer survival, occult metastatic disease becomes evident. <span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 86.4%; vertical-align: super;">5 <span style="color: #298000; font-family: 'Comic Sans MS',cursive;">

Below is a table that lists the overall survival rates of each primary tumor anatomic site and then also breaks them down into each stage.

⁵ ||

-T1 or T2 lesions can be treated with irradiation or surgery alone. Surgery consists of radical tonsillectomy and, for T3 to T4 tumors, partial removal of the mandible and ipsilateral neck disection. -T1 - T3 tumors with radiation alone should recieve between (60 to 75 Gy in 6 to 8 weeks, depending on stage). Regional lymph nodes are treated with 50 Gy and subclinical disease to 75 Gy, epending on nodal involvement. Interstitial brachytherapy has been used to deliver additional dose (25 to 30 Gy) to the primary tumor. -T3-T4 combination of radiation and surgery works better then using one modality alone. Preoperative doses of 30 to 50 Gy in 3 to 5.5 weeks are administered to the primary tumor and ipsilateral (or both) necks. These lesions are treated with radiacal tonsillectomy with ipsilateral neck dissection, followed by irradiation (50 to 60 Gy), depending on the status of the surgical margins and the extent of cervical lymph node involvement.
 * Treatments: || **__Tonsillar Fossa__**

- T1 lesions are treated with wide surgical resection or irradiation alone (60 to 65 Gy in 6 to 7 weeks) -T2 lesions require more extensive surgical procedures or may be treated alone to (65 to 70 Gy). You can also recieve interstitial brachytherapy (20 to 30Gy) in the primary tumor with combined external radiation therapy to (50 Gy). - For more extensive lesions, preoperative or postoperative irradiation can be used in doses similar to those used in the tonsils. - The use of adjuvant chemotherapy in patients with advanced disease has not been clearly shown to improve prognosis. - IMRT or altered fractionation (b.i.d) can be used to increase the overall dose without enhancing morbidity.
 * __Faucial Arch__**

Primary Tumor -T1 = 65 Gy -T2 = 70 Gy T3-T4 = 70-75 Gy
 * __With Irradiation alone...__**

Cervical lymph nodes N0 = 50 Gy N1 = 66 Gy (reduced fields after 50Gy) N2a,b = 70 Gy (reduced fields after 50Gy) N3 = 40-45 Gy to primary tumor and ipsilateral or both necks

Preoperative irradiation / Postoperative irradiation Negative margin specimen = 50 Gy T3-T4 or N2b, N3 or positive margins = 50 Gy to primary site and both necks plus boost to selected volumes to total dose of 60 - 66 Gy Daily dose fractionation = 1.8-2.0 Gy -

__**Volume Treated**__ - Tumors of the tonsillar region and faucial arch can be treated with the same portals and doses of irradiation. - Standard arrangement consists of opposing lateral portals. - The portal extends posteriorly around the external auditory canal, forming a line joining the tip of the mastoid to approximately 1 cm above the foramen magnum. The anterior margin is set up by clinical examination, with at least a 2 cm margin beyond any clinical evidence of disease. Inferiorly, the portal extends to the thyroid notch, except in patients with downward tumor extension with paryngeal wall involvement; in these cases, the margin must be placed below that level. Posteriorly, the posterior cervical lymph nodes should be covered. - After a tumor dose of approximately 40 to 45 Gy, the posterior margin of the lateral portal is brought anteriorly to the midportion of the vertebral bodies to spare the spinal cord.

__**Base of Tongue**__

- T1-T2 surgical resection consisting of mandibulotomy and neck dissection is recommended for T1 and T2 cancers. -T1 and T2 BOT tumors without significant infiltration and surface, or exophytic T2 and T3 lesions of the glossopharyngeal sulcus, are controlled by high-dose radiation. - Large, unresectable BOT cancers that cross the midline and infiltrate and fix the tongue are often irradiated palliatively to achieve as much tumor regression as possible. - Surgery and radiation are best suited for larger tumors that extend beyond the base of tongue or infiltrate and partially fix the tongue. -Doses of 60 Gy and bilateral fields covering the primary site and upper necks are necessary due to lymphatic spread. -There are no significant benefit associated with adjuvant or neoadjuvant chemotherapy.

__**Techniques**__ -Portals should encompass the primary tumor and locoregional extensions. Portals should extend superiorly to the base of skull and floor of the sphenoid sinus to include the retropharyngeal lymphatics, anteriorly to inclue the faucial arch and a portion of the oral tongue, inferiorly to include the supraglottic larynx, and posteriorly to include the posterior cervical triangle. -The primary tumor and upper neck are irradiated using opposing fields. Both the lower neck are irradiated through a single AP field, with a midline block. -The spinal cord is shielded after 40 to 45 Gy, and the posterior cervical triangles are boosed using electrons. -Doses to the primary tumor and palpable lymph nodes are 65 to 75 Gy delivered in 6.5 to 7.5 weeks. 3

10

<span style="color: #298000; font-family: 'Comic Sans MS',cursive;">Conventional portal arrangement for cancer of the oropharynx. Field size reduction delineated by the arrows happens after 43 to 45 Gy in order to protect the spinal cord. <span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 80%; vertical-align: super;">11 <span style="color: #298000; font-family: 'Comic Sans MS',cursive;">"Convention isodose plan showing delivery of 65 to 66 Gy to the primary tumor volume and 50 Gy electively to the neck." <span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 80%; vertical-align: super;">11 <span style="color: #298000; font-family: 'Comic Sans MS',cursive;"> A) Digital Composite Radiograph showing a lt lat portal encompassing a T2N1M0 base of tongue carcinoma. B) Sagittal view showing the structures included in the irradiated field. The portals are reduced after 40-45 Gy to exclude the spinal cord which is delineated the by the dark line on the view. C) Anterior lower neck portal D) An axial view through the center part of the tumor showing the extension of the primary tumor and the metastatic node. <span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 80%; vertical-align: super;">1

<span style="color: #298000; font-family: 'Comic Sans MS',cursive;">A)Digital Compostite Radiograph showing a lt lat portal encompassing a T4N3M0 squamous cell carcinoma of the right tonsil extending into the base of the tongue, level II, and level III lymph nodes on the right side. B) Sagittal view showing the structures included in the fields. The portals would be reduced at 40-45 Gy to exclude the spinal cord and it would be designed based on the outlined GTV. C) Anterior lower neck portal. D) An axial view through the central part of the tumor showing the extent of the disease. <span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 80%; vertical-align: super;">1 <span style="color: #298000; font-family: 'Comic Sans MS',cursive;">A) AP radiograph of 192-R implant in a patient with a recurrent carcinoma of the tonsil and retromolar trigone. B) Lateral radiograph showing the position of the dummy wires used to determine the location of the sources when inserted. <span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 80%; vertical-align: super;">11 || <span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 110%;">Table provided by Wikibooks<span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 80%; vertical-align: super;">9 || <span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 110%;">2. Chao KS, Perez CA, Brady LW. Radiation Oncology Management Decisions. 2nd edition. Philadelphia, PA: Lippincott Williams & Wilkins. 2002. 235-237.   3. Chao KS, Perez CA, Brady LW. Radiation Oncology Management Decisions. 2nd edition. Pg. 237-245. Philadelphia, PA: Lippincott Williams & Wilkins. 1999,2002. 4. Washington,C.M & Leaver, D.(Eds.).(2004). //Principles and Practice of Radiation Therapy// (Second ed). Pg.718.St. Louis, Missouri; Mosby Inc. <span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 120%;"><span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 90%;">5. Rubin P. //Clinical Oncology: A Multidisciplinary Approach for Physicians and Students.// 8th edition. Philadelphia, PA. W.B. Saunders Company. 2001; P. 430. <span style="color: #0000ff; font-family: Georgia,serif;">6. Coia LR, Moylan DJ. //introduction to Clinical Radiation Oncology.// 3rd edition. Madison, Wisconsin: Medical Physics Publishing. 1998; 85-86. 7. Washington,C.M. & Leaver, D. //Principles and Practice of Radiation Therapy.3rd edition. St. Louis, Missouri; Mosby Inc.2010: 723.// 8. //Lip and Oral Cavity Cancer Treatment: Cellular classification//. Retrieved January 6,2010, from the National Cancer Institiute website: [] <span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 110%;">9. Radiation Oncology/Toxicity/Emami. Wikibooks. Available at: []. <span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 110%;">Accessed: January 5, 2010. 10. Department for Work and Pensions. Cancers of the Lip, Mouth, and Oropharynx. Available at: []. Acessed January 14,2010. <span style="color: #298000; font-family: 'Comic Sans MS',cursive;">11. Perez CA, Brady LW, Halperin ED, Schmidt-Ullrich RK. //Principles and Practice of Radiation Oncology.// 4th edition. Philadelphia, PA: Lippincott Williams & Wilkins. 2004: 1034. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"><span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Holly is the<span style="color: #0000ff; font-family: 'Times New Roman',Times,serif;"> royal blue. Kim is the <span style="color: #008080; font-family: 'Times New Roman',Times,serif; font-size: 121%;"> teal green <span style="font-family: 'Times New Roman',Times,serif; font-size: 131.76%;">. <span style="font-family: 'Times New Roman',Times,serif; font-size: 119.79%;">Kristy is the <span style="color: #ff00ff; font-family: 'Times New Roman',Times,serif; font-size: 119.79%;">fushia/bright purple <span style="font-family: 'Times New Roman',Times,serif; font-size: 119.79%;">. <span style="font-family: 'Times New Roman',Times,serif; font-size: 121%;">Stacy is the <span style="color: #298000; font-family: 'Comic Sans MS',cursive;">darker green <span style="font-family: 'Times New Roman',Times,serif; font-size: 121%;">. Shae is the <span style="color: #ff0000; font-family: 'Times New Roman',Times,serif; font-size: 121%;"> red <span style="font-family: 'Times New Roman',Times,serif; font-size: 121%;">. <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">
 * TD5/5: || [[image:TD5.5_Chart.jpg]]
 * References: || <span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 90%;"><span style="color: #298000; font-family: 'Comic Sans MS',cursive; font-size: 120%;">1. Chao KS, Perez CA, Brady LW. //Radiation Oncology Management Decisions. 2nd edition.// Philadelphia, PA: Lippincott Williams & Wilkins. 1999, 2002; P. 237-251.