Familial Nasopharyngeal Carcinoma 6

Selection and Delineation of Target Volumes 17in Intensity-Modulated Radiation Therapyfor Nasopharyngeal CancerJiade J. Lu, Vincent Grégoire, and Shaojun LinCONTENTS17.1 Introduction 21317.2 Anatomy 21417.2.1 Anatomy of the Nasopharynxand its Surrounding Structures 21417.2.2 Classification of Lymph Node Levelsin the Neck 21517.2.2.1 Retropharyngeal Lymph Nodes 21817.2.2.2 Retrostyloid Space 22117.2.2.3 Supraclavicular Lymph Nodes 22117.3 Target Volume Selection and Delineationof the Primary Disease 22117.3.1 Defining the Gross Tumor Volumeof the Primary Disease 22317.3.2 CTV of the Primary Disease 22517.4 Target Volume Selection and Delineationin the Neck 22617.4.1 Diagnosis of Cervical LymphAdenopathy 22617.4.2 Patterns of Cervical Lymph NodeMetastases 22617.4.2.1 Retropharyngeal Lymph Nodes 22617.4.2.2 Level II Lymph Nodes 22717.4.2.3 Level V Lymph Nodes 22817.4.2.4 Level III and IV Lymph Nodes 22817.4.2.5 Level I Lymph Nodes 22817.4.2.6 Supraclavicular Lymph Nodes 22817.4.2.7 “Skip” Metastasis of Lymph Nodes 22917.4.2.8 Bilateral Cervical Node Involvement 229Jiade J. Lu, MD, MBADepartment of Radiation Oncology, National University CancerInstitute, National University Health System, NationalUniversity of Singapore, 5 Lower Kent Ridge Road, Singapore119074, Republic of SingaporeVincent Grégoire, MD, PhDRadiation Oncology Department and Center for MolecularImaging and Experimental Radiotherapy, UniversitéCatholique de Louvain, St-Luc University Hospital, 10 AvenueHippocrate, 1200 Bruxelles, BelgiumShaojun Lin, MDDepartment of Radiation Oncology, Cancer Hospital of FujianMedical University, 91, Fumalu Maluding Road, Fuzhou, Fujian350014, PR China17.117.4.3 Selecting Clinical Target Volumesin the Neck 22917.4.3.1 Clinical Target Volumesin N0 Disease 23017.4.3.2 Clinical Target Volumes in N+ Diseasewith Extracapsular Extension 23017.5 Conclusions 231References 231IntroductionRadiation therapy is the mainstay therapeuticmodality for nasopharyngeal cancer (NPC), andhigh-dose radiation is required for curative treatmentof the disease. Nasopharynx is in close proximityto the critical structures such as brainstem andbrain (temporal lobes), parotid glands, and spinalcord. Irradiating structures close to the nasopharynxmay cause symptoms that substantially affectthe quality of life of patients after treatment; preciseradiation therapy for this malignancy has alwaysbeen the focus of technology development.The implementation of intensity-modulated radiationtherapy (IMRT) allows a significant improvementin the control of radiation dose distribution andis considered more advantageous for definitive therapyfor nonmetastatic NPC. However, the utilizationof IMRT in the treatment of NPC requires a differentmindset when compared with conventional radiotherapy.One of the most important differences is theselective treatment of structures surrounding the primarydisease and neck nodes required with IMRT.Target volumes harbor gross and subclinical diseasesthat need to be accurately determined and delineatedbefore the planning of IMRT can be initiated. Therefore,the utilization of IMRT in the treatment of NPCrequires full understanding of the criteria of radiologicaldiagnosis of the primary disease and cervical