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.

The staging of hypopharyngeal cancer is based both on the subsite of the pharynx involved and the size of the tumor, the presence of vocal cord fixation, and the extent of lymph node metastases (Table 90-11). Distant metastases at the time of diagnosis are rare. Staging evaluation is critical for treatment planning and must include endoscopic evaluation to determine precisely the tumor margins, extent of invasion of adjacent structures, and presence of second primary tumors or skip areas. Determination of the precise site of origin and inferior extent of a tumor can be difficult with large tumors or with those obstructing the esophageal inlet.

Because of the necessity to remove the larynx as part of the surgical treatment of most hypopharyngeal cancers, radiation therapy as treatment has been extensively investigated. Retrospective analyses have consistently demonstrated that survival rates are lower and locoregional failure rates higher with radiation alone as compared with surgery or surgery and radiotherapy. However, for small (T1) cancers of the hypopharynx, and particularly for superficial posterior pharyngeal wall lesions, radiation therapy alone has been used effectively, with surgery reserved for salvage. Radiation therapy offers the advantage of treating bilateral occult lymph node disease, including that of retropharyngeal nodes, which are frequently involved when cancer arises from the posterior pharyngeal wall. Small cancers of the hypopharynx can be treated equally effectively with surgical resection, often with sparing of the larynx for posterior wall lesions or with supraglottic laryngectomy for superficial cancers of the medial or lateral pyriform when the apex mucosa is tumor-free. Most patients, however, present with advanced primary tumors (T2 to T4) and positive lymph nodes. In such patients, local control rates with radiation alone decrease to 50% and salvage surgery is rarely successful. Thus, surgical management has become the mainstay of treatment for most hypopharyngeal cancers. Resections may entail partial pharyngectomy, pharyngolaryngectomy, or total pharyngectomy combined with neck dissection and the associated difficulties in post-treatment function. While free-flap reconstructions have improved results, there still remain the difficulties of lack of sensation and dysphagia.