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.

Tumors arising in the lower laryngopharynx or postcricoid mucosa often spread to involve the esophagus. Distal submucosal spread into the esophagus can be extensive and requires partial or total esophagectomy. Reconstruction with transposition of the stomach (gastric pullup), jejunal free graft, or tubed myocutaneous free flap is currently recommended. With improved locoregional control following the advent of total laryngopharyngectomy and postoperative radiation therapy, disease recurrence more commonly occurrs in distant sites (ie, the lung). Treatment approaches with combined preoperative or postoperative radiation have improved the control of lymph node disease, but survival rates have not improved substantially over those with surgery alone because of the increased rates of distant metastases. Postoperative radiation is currently preferred to preoperative radiation because of its lower local recurrence rates, fewer complications, and less difficulty in accurately assessing tumor margins. The clear superiority of combined surgery and radiation over surgery alone has not been established. Although several studies demonstrate improved survival with combined therapy, direct comparisons with surgery alone are difficult because of differences in patient selection factors, tumor extent, and degree of lymph node involvement. Well-designed randomized trials to compare surgery alone with combined therapy have not been performed.

The presence of lymph node metastases, extracapsular lymph node involvement, and direct extension of the primary tumor into the soft tissues of the neck are major negative prognostic factors. Overall 5-year survival rates range from 10% to 30% for posterior pharyngeal wall cancers and from 20% to 40% for pyriform sinus cancers (

Table 90-12). Locoregional recurrence continues to account for the greatest number of deaths from disease.

Distant metastases are rarely evident at the time of presentation. The development of distant metastases may appear many years after primary therapy and seems to correlate with extent of regional lymph node involvement. The rates of distant metastases range from 20% to 50% and increase with the extent of lymph node disease. In a recent study by the EORTC, induction chemotherapy and radiation therapy were utilized for stages II and III hypopharyngeal cancers. In these randomized trials, which compared laryngeal preservation with combination chemotherapy and radiation therapy with surgery with postoperative radiation therapy, survival (including surgical salvage) remained equal. Approximately 30% of patients with stage III disease can preserve their larynx. The functional analysis of these patients regarding speech and swallowing remains unreported to date, however.

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Provided by ArmMed Media
Revision date: July 9, 2011
Last revised: by Andrew G. Epstein, M.D.