Image-Guided Intensity-Modulated Radiotherapy for Single Vocal Cord Irradiation in Early Glottic Cancers

The larynx anatomy is graphically presented in figure 1.1 . The vocal cords in the center of the larynx are muscular bands covered by thin mucosa layers. Together, the right and left vocal cords have a V-shape, when viewed from cranial. The vocal cords play key roles in the control of the airflow during breathing, the protection of airway, and in the production of sound for speech. Cancer of the larynx is one of the most common cancers in Europe, with about 52,000 new cases annually, 90% occurring in men. 95% of all cancers of the larynx are squamous cell carcinomas [65]. Cancer of the larynx is mainly caused by consumption of tobacco and alcohol. Nevertheless, tobacco dominates the risk for cancer of the vocal cords. Over 90% of the present incidences of laryngeal cancers could be prevented by avoiding smoking and alcohol consumption. The most common symptoms observed in early glottic cancers are; the presence of hoarseness, sore throat, shortness of breath, and the feeling of a lump in the throat. Hoarseness, which is a an early symptom for glottic lesions, is the main symptom which causes patients to seek medical consultation [65]. A complete ear, nose, and throat check (with mirrors and laryngscopes) and histology examination are common steps in the examination of suspected laryngeal cancer patients. Vocal cord mobility and exact tumor extension are carefully assessed to aid specifying the exact stage (TNM staging) of the tumor [65]. The stage of the tumor is important for establishing the treatment policy. This thesis discusses treatment of early stage glottic cancers (Carcinoma in situ (Tis), and tumors limited to one vocal cord (T1a), with no regional/distant lymph node metastasis (N0M0)).

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