Oropharyngeal Tumours

The oropharynx includes the base of tongue, the inferior surface of the soft palate and uvula, the anterior and posterior tonsillar pillars, the glossotonsillar sulci, the pharyngeal tonsils, and the lateral and posterior pharyngeal walls. The borders of the oropharynx include the circumvallate papillae anteriorly, the plane of the superior surface of the soft palate superiorly, the plane of the hyoid bone inferiorly, the pharyngeal constrictors laterally and posteriorly, and the medial aspect of the mandible laterally.
In the reality of primary care it is not important to be so precise about the anatomy and large tumours may extend beyond this space. Of tumours of the oropharynx, 90% are squamous cell carcinomas. Other tumours include lymphoma and salivary gland tumours of the minor glands.

It is a fairly uncommon malignancy with around 500 new cases a year and men are involved about 3 or 4 times as frequently as women.¹

Smoking, heavy alcohol consumption and poor dentition are the principle risk factors in western countries.² Several carcinogens, occupational exposures and vitamin deficiencies may also be involved.³

Presenting symptoms include:

• Sore throat
• Bleeding causing haemoptysis
• Dysphagia
• Pain referred to the ear
• Changes in the voice
• Trismus suggests involvement of the pterygoid musculature
• Presentation may be the lump of a lymph node metastasis.

• A mass may be visible.
• Palpate for nodes. Lymph node metastases generally occur in the upper jugular chain, although they can "skip" to lower levels and spread. Bilateral metastases are more common with tongue base and soft palate lesions, especially with midline lesions.

Biopsy is essential for diagnosis. Imaging studies should focus on invasion through the pharyngeal constrictors, bony involvement of the pterygoid plates or mandible, invasion of the parapharyngeal space or carotid artery, involvement of the prevertebral fascia, and extension into the larynx.

This is as for the oral cavity. Most tumours are irregular in shape and hence the term diameter refers to the maximum diameter.

• Treatment of oropharyngeal SCC increasingly moves towards chemotherapy and radiotherapy rather than surgery. Tumours are often poorly differentiated and respond well to radiotherapy. Chemotherapy may also function as a radiation sensitiser.
• In recent studies, the local control rate has achieved 90% even in stage IV disease, although overall survival has not improved over more traditional surgery and radiation therapy.⁴
• Surgery is necessary if the primary tumour involves the mandible and resectable recurrent disease and has a role in very early, superficial lesions that do not merit a full course of radiation.
• Extensive surgery of the base of the tongue significantly alters the patient's ability to swallow. Reconstruction of the tongue with preservation of the larynx requires surgical techniques that maintain tongue mobility and suspend the larynx and neotongue to prevent aspiration.

Surgical resection or contracture after radiotherapy of the soft palate may result in velopharyngeal insufficiency (VPI). This causes nasal regurgitation of liquids and solids and hypernasal speech. Surgical augmentation of the soft palate can be performed or a palatal obturation may be used. A palatal obturator requires cleaning and is not permanent but patients are able to remove them during sleep. With surgical augmentation of the palate, the balance between reducing VPI and causing obstructive sleep apnoea is difficult. For patients who have had the base of the tongue resected, an inferiorly directed palatal obturator assists in achieving contact at the tongue base that is necessary for the projection of food posteriorly during the oral and pharyngeal phases of swallowing. There may be less problems with swallowing after chemotherapy than with surgery and radiotherapy.⁵

The optimum balance between the various treatments needs to be ascertained.^6,7 Survival figures can be remarkably good but should be interpreted with caution for any single case with such a varied group of conditions.