NEOPLASIA OF THE ORAL CAVITY

The anatomical contents of the oral cavity include the upper and lower alveolus, teeth, lips and the anterior two-thirds of the tongue. Virtually all oral cavity cancers are of the malignant squamous cell variety. Adenoid cystic carcinoma can arise from minor salivary glands but is rare.

Premalignant lesions in the oral cavity include leucoplakia and erythroplakia. In virtually all neoplasia of the oral cavity one or more of several aetiological factors are present. Smoking and alcohol abuse are very common. Chronic dental infection, e.g. caries, may result in malignant change, as may lesions seen in tertiary syphilis.

Carcinoma of the lipCarcinoma of the lip is common in outdoor workers and in regions close to the

equator, presumably due to the effects of ultraviolet light. Tobacco smokers show a higher incidence of lip cancer. Historically, smoking a clay pipe was the major cause.

Clinical featuresThe lower lip, perhaps due to its greater size, is most frequently affected.

Dyskeratosis usually manifests as a white patch on the lip, termed “actinic cheilitis”. Included in the differential diagnosis is keratoacanthoma, syphilis and tuberculosis. A biopsy will confirm the diagnosis.

ManagementA lip shave and advancement of the vermilion is performed in actinic cheilitis.

Any neoplastic lesion requiring less than a third of the lip to be excised can be removed by modified V incision and primary closure. Larger tumours will require local skin flaps for reconstruction. Radical neck dissection will be necessary if metastatic nodal disease is present. Radiotherapy in small early lesions also produces excellent results, and control may be achieved using the argon laser.

Carcinoma of the tongueThe incidence of tongue cancer is diminishing due to improvements in dental

hygiene and the fall in popularity of chewing tabacco. The lateral border of the tongue is the commonest site affected.

Clinical featuresA persistent ulcer, usually painless, is the common presentation. If allowed to

grow, the lesion will ultimately cause tongue fixation and invade the mandible. The patient will then experience difficulty in chewing, swallowing and speech. About a third of patients will have a metastatic neck gland at presentation, which may be on the contralateral side of the neck due to the decussating nature of the lymphatic drainage in this area. The diagnosis is confirmed by biopsy.

Management Treatment of small lesions without neck metastases is by either surgery or

radiotherapy. A wedge excision may be emlpoyed, but implanted radium needles can produce the same cure rate. Larger lesions will require a partial glossectomy, resection of the mandible and neck dissection.

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Carcinoma of floor of mouthSquamous carcinoma at this site tends to present late. Most lesions will have

already invaded the periosteum and bone of the mandible.

Clinical featuresDysphagia or odynophagia ( pain on swallowing) are common symptoms.

Pain is usually a major feature and signifies deep invasion. There may also be referred otalgia. An orthopantogram or CT may reveal bone erosion of the mandible. Biopsy is mandatory for tissue diagnosis and prior to embarking on major surgery.

Management Radiotherapy is usually not offered as a primary form of treatment as any

subsequent excision has a high risk of producing osteoradionecrosis of irradiated bone. After surgical excision, the soft tissue defect is reconstructed using either a pedicled or free flap. Mandibular reconstruction is also feasible. A radical neck dissection will be required as the presence of nodal disease is almost universal.

Carcinoma of the alveolar ridgeThe lower alveolar ridge is most commonly affected. In the elderly, an

illfitting denture may be the presenting symptom. Most lesions will have spread to bone and the adjacent floor of mouth.

The mandible is either invaded directly by tumor or via the inferior dental nerve canal. In the latter case the contiguous spread may be as far posteriorly as the skull base. Treatment is along similar lines to that of carcinoma of the floor of mouth.

Carcinoma of the hard palateSquamous carcinoma is rare in this site. Adenoid cystic carcinoma is not

uncommon, as are benign minor salivary gland tumours. The former cancer tends to extend along the perineural spaces of the greater palatine nerves and may spread into the cranium.

Treatment of adenoid cystic carcinoma is surgery, possibly followed by postoperative radiotherapy. Any defect in the hard palate can be occluded with a dental obturator.

Carcinoma of the buccal liningThe buccal lining is a very common site for cancer on the Indian subcontinent,

probably resulting from metaplastic change induced by betel nut chewing. The lesion may be ulcerative or exophytic.

A biopsy will confirm the diagnosis. Early small lesions may be successfully excised and primarily sutured. Wider resection will require skin grafting. Radiotherapy should be used in extensive lesions, which are usually incurable due to invasion of the pterygoid muscle region.

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