Laryngeal Cancer: An Overview for Singing Teachers

INTRODUCTIONSINGING TEACHERS NEED TO BE AWARE of the many health issues that potentially affect their students. Laryngeal cancer, though fortunately rare, can have a significant impact on voice. Laryngeal cancer accounts for only 1% of new cancer diagnoses in the United States`,1 but it can have profound effects on those who use their voices in a professional capacity. Early identification and intervention are crucial for effective voice preservation as well as overall survival. The singing teacher should be familiar with this disease process and be equipped to identify those most at risk so that early referral and knowledgeable support can be provided to singers who look to their teachers for answers.ANATOMYThe larynx has three main subdivisions: the supraglottis (above the vocal folds), the glottis (the vocal folds themselves), and the subglottis (below the vocal folds). The supraglottis extends from the tip of the epiglottis (the leaf-like cartilage that prevents food from entering the airway) to the apex of the ventricles (spaces between the false and true vocal folds) just above the vocal folds (Figure 1). It includes structures such as the epiglottis, aryepiglottic folds, arytenoid cartilages, false vocal folds, and ventricles.The glottis extends from the ventricle to about 0.5-1 centimeter inferior to the free margin of the vocal folds. Glottic cancers of the larynx arise more commonly in the front half of the vocal folds and can invade backward, occasionally involving surrounding structures. Invasion of the vocalis (medial thyroarytenoid) muscle and cricoarytenoid joints can occur with deep and posterior spread, respectively. These types of invasion can lead to changes in voice quality by limiting movement of the vocal folds in addition to the more apparent effect on mucosal wave propagation.2The subglottis begins one centimeter inferior to the free edge of the vocal fold. It spans the lumen of the cricoid cartilage and ends at the beginning of the trachea. Subglottic laryngeal cancers usually occur from direct extension of glottic lesions and can invade surrounding structures, causing significant breathing and voice problems.Laryngeal cancer represents a change in cellular structure of the normal lining of the larynx. Progression usually occurs over time as a result of chronic irritants or risk factors. Nearly all laryngeal cancers are squamous cell carcinoma; however, adenocarcinoma, minor salivary gland tumors, carcinoid (or serotoninproducing) tumor, oat cell carcinoma, and undifferentiated carcinoma have also been described in the larynx.3EPIDEMIOLOGYLaryngeal cancer affects an estimated 3.4 out of 100,000 individuals, has a male predominance, and usually occurs later in life, with almost 60% of cases occurring between the ages of 55 and 75. The incidence of and mortality from laryngeal cancer have decreased significantly over the past 10-15 years, likely as a result of increased awareness of risk factors and more rapid diagnosis.4 Risk factors include smoking, alcohol, human papilloma virus infection, laryngopharyngeal reflux, and radiation exposure, among others (Table 1). The single most significant and preventable risk factor in the development of laryngeal cancer is smoking, which is associated with almost 95% of supraglottic and glottic cancer. A linear association exists between the number of cigarettes used and the risk of developing cancer.5 The concurrent usage of tobacco and alcohol has a synergistic effect on the risk of developing laryngeal cancer.While smoking and alcohol represent the two most important risk factors in the development of laryngeal cancer, infectious, inflammatory, and caustic factors also can play a role. Human papilloma virus, or HPV, is a well established cause of cervical cancer and has been linked to cancers of the oral cavity, oropharynx, and larynx. HPV interferes with DNA repair and programmed death of damaged cells. …