Cancer of the hypopharynx is uncommon; approximately 2,500 new cases are diagnosed in the United States each year. The peak incidence of this cancer occurs in males and females aged 50 to 60 years. Excessive alcohol and tobacco use are the primary risk factors for hypopharyngeal cancer.[3,4] In the United States, hypopharyngeal cancers are more common in men than in women. In Europe and Asia, high incidences of pharyngeal cancers, namely, oropharyngeal and hypopharyngeal, have been found among men in France, in the counties of Bas-Rhin and Herault; Switzerland, in the section of Vaud; Spain, in the Basque Country region; Slovakia, Slovenia, and India, in the cities of Bombay and Madras. This cancer is extremely rare in children.
Upper hypopharyngeal cancers appear to be associated more with heavy drinking and smoking, whereas the lower hypopharyngeal, or postcricoid, cancers are more often associated with nutritional deficiencies.[1,8] Although earlier reports from northern Europe, particularly from Sweden, indicated a link between Plummer-Vinson syndrome, which consisted of sideropenic anemia and epithelial changes of the aerodigestive tract, and other nutritional deficiencies in women, cases of hypopharyngeal cancer among women are currently more likely to be associated with excessive use of alcohol and tobacco, rather than with deficiency diseases.[2,9,10,11]
Anatomically, the hypopharynx extends from the plane of the hyoid bone above to the plane of the inferior border of the cricoid cartilage below. The hypopharynx is composed of the following three parts and does not include the larynx:
- The pyriform sinus.
- The postcricoid area.
- The posterior pharyngeal wall.
The lymphatic drainage from the pharynx is into the jugulodigastric, jugulo-omohyoid, upper and middle deep cervical, and retropharyngeal nodes. In the United States and Canada, 65% to 85% of hypopharyngeal carcinomas involve the pyriform sinuses, 10% to 20% involve the posterior pharyngeal wall, and 5% to 15% involve the postcricoid area. Pyriform sinus and postcricoid carcinomas are typically flat plaques with raised edges and superficial ulceration. In contrast, posterior hypopharyngeal wall tumors tend to be exophytic and are often large (i.e., 80% >5 cm) at presentation. Hypopharyngeal carcinomas tend to spread within the mucosa, beneath intact epithelium, and are prone to skip metastasis and to resurface at various locations remote from the primary site.[1,13] Because of this fact and the abundant lymphatic network of the region, a localized hypopharyngeal tumor is the exception.
Almost all hypopharyngeal cancers are mucosal squamous cell carcinomas (SCCs). Multiple primary tumors are not uncommon. Approximately 25% of patients in a retrospective study of 150 cases were found to have second primary tumors. Field cancerization may be responsible, in part, for the multiple, synchronous, primary malignant neoplasms that occur in patients with hypopharyngeal cancer.[1,14,15,16] The concept of field cancerization, originally described in 1953, proposes that tumors develop in a multifocal fashion within a field of tissue that has been chronically exposed to carcinogens.