Chapter 23: Benign and Malignant Lesions of the Oral Cavity, Oropharynx, and Nasopharynx

BENIGN AND MALIGNANT LESIONS OF THE ORAL CAVITY AND OROPHARYNX

General Considerations

The oral cavity is bounded anteriorly by the vermilion border of the lip, superiorly by the hard-soft palate junction, laterally by the tonsillar pillars, and inferiorly by the circumvallate papillae of the tongue. Subsites of the oral cavity include the tongue (anterior two-thirds), buccal mucosa, floor of mouth, hard palate, upper and lower gingiva (alveolar ridges), and retromolar trigone. The lip has traditionally been considered part of the oral cavity but was recently removed from the American Joint Committee on Cancer (AJCC) 8th edition staging system. Approximately 23,110 new oral cavity cancers are diagnosed annually in the United States, and approximately 5370 patients die of their disease per year. Men are affected 2 to 4 times more often than women for all racial and ethnic groups. The incidence of oral cancer increases with age, with the median age at diagnosis of 62 years, although there is a trend of increasing incidence of tongue cancer among young people.

Tobacco use (both chewing and smoking), alcohol, and betel nut chewing are well-established causes of oral cavity cancer, and their carcinogenic effects are synergistic. Other etiologic factors include poor oral hygiene and immunosuppression. The majority (90%) of cases of lip cancer are related to chronic sun exposure.

The oropharynx is posterior to the oral cavity and is bounded by the soft palate superiorly and hyoid inferiorly. Oropharyngeal subsites include the base of tongue (posterior third), palatine tonsil, soft palate, and posterior pharyngeal wall. These lesions are often silent in early stages and, consequently, frequently present with advanced stage. Cancer of the oropharynx occurs in an estimated 7570 patients in the United States each year, resulting in approximately 1340 deaths. Men are afflicted 3 to 5 times more frequently than women. The demographics of oropharyngeal cancers have changed over the last 2 decades, with 60% to 80% of newly diagnosed oropharyngeal cancers now attributable to human papillomavirus.

Staging

Staging for oral cavity cancers is determined according to the 2018 AJCC TNM (tumor, node, metastasis) staging system (Table 23–1). Staging for HPV-associated oropharynx cancers is shown in Table 23–2, and for non-HPV-related oropharynx cancers in Table 23–3.