Cancer of the Hypopharynx

The hypopharynx extends from the hyoid bone superiorly to the lower border of the cricoid cartilage inferiorly. It is composed of four subsites: (1) the piriform sinuses, situated lateral to the larynx; (2) the postcricoid area, lying immediately behind the larynx; (3) the posterior pharyngeal wall; and (4) the marginal area where the medial wall of the piriform sinus and the false vocal cord meet superiorly at the aryepiglottic fold. Laterally, the piriform sinuses are bounded by the alae of thyroid cartilage and the thyrohyoid membrane. The hypopharynx, lined by stratified squamous epithelium, has a muscular wall consisting of the middle and inferior constrictor muscles. The retropharyngeal space posterior to the hypopharynx, which contains lymphatics and loose areolar tissue, separates the visceral compartment of the neck from the prevertebral muscles with their overlying prevertebral fascia.

Pathology

Over 95% of hypopharyngeal cancers are squamous carcinomas, which usually present as infiltrating ulcerative lesions. The incidence of poorly differentiated cancer is higher in the hypopharynx than in other regions. The size of these cancers can be deceptive on clinical evaluation because of submucosal lymphatic extension. Minor salivary gland cancers and lymphomas occasionally occur in the hypopharynx, where they usually present as submucosal tumors. Benign hypopharyngeal lesions include webs, strictures, and pharyngoesophageal (Zenker's) diverticula.

Cancer of the hypopharynx has a high propensity for lymphatic invasion, with most patients having cervical lymph node metastases at the time of initial presentation. The hypopharynx—especially the piriform sinus—must always be examined in an adult with cervical lymph node metastases and no obvious primary cancer site. Occult cervical lymph node metastases (ie, clinically negative but histologically positive) are also common, causing the overall incidence of cervical lymph node metastases at presentation to be approximately 75%. The principal cervical lymph node groups involved are the upper, mid, and lower jugular nodes (levels II, III, and IV); the retropharyngeal nodes of Ranvier; and, less frequently, the cervical lymph nodes along the spinal accessory nerve in the posterior triangle (level V).

Clinical Findings

The chief symptoms of hypopharyngeal cancer are pain, dysphagia, and weight loss. Pain can be localized to the site of the cancer or can be referred to the ipsilateral ear. About 25% of patients, especially those with lesions of the piriform sinus, present with palpable cervical lymphadenopathy and no other symptoms. Advanced cancers can invade the larynx and cause vocal cord paralysis and hoarseness. Direct laryngopharyngoscopy and biopsy are necessary to confirm the diagnosis and assess the extent of the cancer.

T STAGE: HYPOPHARYNGEAL CANCER

T1 Tumor limited to one subsite of the hypopharynx and 2 cm or less in size T2 Tumor invades more than one subsite of the hypopharynx or an adjacent site, or measures more than 2 cm and no more than 4 cm in size, without fixation of the hemilarynx T3 Tumor invades more than one subsite of the hypopharynx or an adjacent site, with fixation of the hemilarynx T4 Tumor invades adjacent structures (eg, cartilage or soft tissues of the neck)

Treatment

The goals of treatment are to cure the cancer and maintain functional continuity of the upper aerodigestive tract. Intensive nutritional therapy is necessary if long-standing dysphagia has resulted in cachexia. Patients with cancer of the hypopharynx also commonly have pulmonary disease that must be assessed and managed preoperatively.

A. Primary Cancer

Surgical resection of hypopharyngeal cancers usually requires laryngopharyngectomy. Small (T1, T2) cancers of the piriform sinuses are curable with radiation therapy. Small (T1 and T2) cancers of the posterior pharyngeal wall can be treated with larynx-preserving local excision. Jejunal and tubed radial forearm free flaps permit excellent hypopharyngeal reconstruction. If a cancer extends to or arises in the cervical esophagus, laryngopharyngectomy and esophagectomy may be required. In this circumstance, a gastric pull-up procedure provides for upper aerodigestive tract continuity.

B. Management of Neck Metastases

The incidence of cervical lymph node metastases is so high with hypopharyngeal cancers that some form of neck treatment is appropriate for all patients. Treatment of both sides of the neck is frequently indicated. Radical or modified neck dissection is indicated for clinically evident cervical lymph node metastases. For the clinically negative neck, when the primary cancer is treated with radiation therapy, the neck is also treated with radiation therapy. If the primary cancer is treated surgically, elective neck dissection is performed. If postoperative radiation therapy will be given to the primary cancer site, radiation therapy can also be given to the neck, making an elective neck dissection unnecessary.

The Hypopharynx - Hypopharyngeal cancers

The hypopharynx represents one of the most lethal sites for SCC. Lymph node metastases are clinically evident at time of diagnosis in 70% to 80% of patients and are indicative of advanced disease. Bilateral and contralateral lymph node metastases occur in 10% to 20% of cases, particularly if tumors cross the midline of the hypopharynx. Primary tumor extension beyond the hypopharynx is common. Hypopharyngeal cancers are characterized by a propensity to spread submucosally to involve the oropharynx or esophagus. Ulcerated deep infiltration and skip areas are common. This leads to difficulties in adequately assessing the margins of the tumor and contributes to poor local tumor control, even with the addition of adjuvant radiation. The majority (more than 75%) of hypopharyngeal cancers arise in the pyriform sinus while 20% occur in the posterior pharyngeal wall. Postcricoid cancers are rare (less than 5% of hypoparyngeal cancers). Posterior pharyngeal wall cancers tend to grow superficially and only involve the prevertebral fascia in advanced lesions. Pyriform cancers spread early to other contiguous structures, such as the larynx, postcricoid area, thyroid gland, and thyroid and cricoid cartilages. Most pyriform sinus cancers arise along the medial wall followed by the lateral wall of the sinus. The postcricoid mucosa is contiguous with the apex of the pyriform and tumor can spread circumferentially to involve the entire lower hypopharynx. Because of the locale of hypopharyngeal cancers and their growth patterns and proximity to the larynx, surgical management often entails total laryngopharyngectomy. » »

Prognosis

In patients with cancer of the hypopharynx, distant metastases appear in 25% of patients—a much higher incidence than with cancers of the oral cavity and oropharynx. The 5-year survival rates for patients with cancer of the hypopharynx receiving appropriate treatment are subsite-specific. Generally, patients with hypopharyngeal cancers do worse than patients with oropharyngeal cancers.

References

Chu PY et al: Surgical treatment of squamous cell carcinoma of the hypopharynx: analysis of treatment results, failure patterns, and prognostic factors. J Laryngol Otol 2004;118:443. Pubmed: 15285863

Urba SG et al: Organ preservation for advanced resectable cancer of the base of tongue and hypopharynx: a Southwest Oncology Group Trial. J Clin Oncol 2005;23:88. Pubmed: 15625363