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.
Clinically, cancers of the hypopharynx tend to be aggressive and demonstrate a natural history that is characterized by diffuse local spread, early metastasis, and a relatively high rate of distant spread. More than 50% of patients with hypopharyngeal cancer have clinically positive cervical nodes at the time of presentation. In 50% of these individuals, a neck mass is the presenting symptom.[2,18,19] In a retrospective study of 78 cases of hypopharyngeal cancer, other symptoms in addition to a neck mass (25.6%) included dysphagia (46.1%), odynophagia (44.8%), voice change (16.3%), and otalgia (14.2%). A voice change due to pyriform sinus or postcricoid lesions is a late symptom that usually indicates invasion into the larynx or the recurrent laryngeal nerve.
In a large, retrospective study of patients with SCC of the larynx and hypopharynx, 87% of patients with pyriform sinus SCC were found to have stage III or stage IV disease; 82% of patients with SCC of the posterior pharyngeal wall were found to have stage III or stage IV disease. As many as 17% of hypopharyngeal SCCs may be associated with distant metastases when clinically diagnosed. This is quite different from the rate of distant metastasis detected at autopsy, which has been reported to be as much as 60%. A relatively high incidence of delayed regional (i.e., 2 or more years after completion of primary therapy) and distant metastatic disease in hypopharyngeal SCC is related to the advanced stage of the disease at diagnosis. Almost 33% of pyriform sinus tumors may be associated with delayed regional metastases.