III. MATERIALES Y MÉTODOS
3.1. Descripción de la zona influencia del proyecto
Oral cancer arises from the surface mucosa, and the clinical diagnosis should be easy. Early detection should lead to better outcome. Oral lesions, unlike those at many other sites in the body, give rise to early symptoms. In general, patients become aware of and usually complain about tiny lesions within the mouth and biopsy may be carried out under local analgesia. Yet, despite all the above, between 27 and 50% of patients present for treatment with tumours greater than 4 cm in diameter. Many of these patients are elderly and frail and therefore delay the effort of visiting their doctor or dentist: they are often denture wearers, accustomed to discomfort and ulceration in the mouth and thus see no urgency in seeking treatment. Furthermore, the practitioner may not be suspicious that a lesion is malignant. Not all oral cancers present as classical non-healing ulcers with heaped-up margins: they can start as small areas of ulceration in the depth of fissures in the tongue, as superficial mucosal erosions, as areas of induration in the absence of discernible ulceration or even as gingival hyperplasia mimicking gingival infection.
The lesion is often treated initially with antifungal therapy, antibiotics, steroids and mouthwashes, thus causing further delay in the ultimate diagnosis and treatment. Another factor is that oral cancer is not
Indications for urgent referral by general dental practitioner
● Any ulcer which persists unhealed for more than 2 weeks
● Any unexplained oral bleeding
● Any area of induration
● All unexplained white patches
● All red or red/white patches
Fig. 10.7 An advanced cancer of the tongue presenting as an ulcer with heaped-up margins and a central area of necrosis.
Presentation of oral cancers
● Classical ulcer with central necrosis and exophytic margins
● Small ulcer in the depth of a fissure
● Superficial mucosal erosion
● Indurated area within soft tissue
● Localized area of gingival hyperplasia
135 135 with unsuspected infiltration into the underlying
muscle. Leukoplakic patches may or may not be associated with the primary lesion. A minority of tongue cancers may be asymptomatic, arising in an atrophic depapillated area with an erythroplakic patch with peripheral streaks or areas of leukoplakia.
Later in the course of the disease a more typical malignant ulcer will usually develop, often several centimetres in diameter. The ulcer is hard in consistency (indurated) with heaped-up and often everted edges (Fig. 10.7). The fl oor is granular, indurated and bleeds readily. Often there are areas of necrosis.
The growth infiltrates the tongue progressively, causing increasing pain and difficulty with speech and swallowing. By this stage pain is often severe and constant, radiating to the neck and ears. Lymph node metastases at this stage are common—indeed 50% of patients may have palpable nodes at first attendance. Because of the relatively early lymph node metastasis of tongue cancer, 12% of patients may present with no symptoms other than ‘a lump in the neck’.
Floor of the mouth (Fig. 10.8)
The fl oor of the mouth is the second most common site for oral cancer. It is defined as the U-shaped area between the lower alveolus and the ventral surface of the tongue; carcinomas arising at this site involve adjacent structures very early in their natural history.
Most tumours occur in the anterior segment of the fl oor of the mouth to one side of the midline.
The lesion usually starts as an indurated mass, which soon ulcerates. At an early stage the tongue and lingual aspect of the mandible become infiltrated. This early
involvement of the tongue leads to the characteristic slurring of the speech often noted in patients with such cancers. The infiltration is deceptive but may extend to reach the gingivae, tongue and genioglossus muscle.
Subperiosteal spread is rapid once the mandible is reached. Lymphatic metastasis, although early, is less common than with tongue cancer. Spread is usually to the submandibular and jugulodigastric nodes and may be bilateral.
Floor of mouth cancer is associated with a pre-existing leukoplakia more commonly than cancer at other sites.
Gingiva and alveolar ridge (Fig. 10.9)
Carcinoma of the lower alveolar ridge occurs pre-dominantly in the premolar and molar regions. The patient usually presents with proliferative tissue at the gingival margins or superficial gingival ulceration.
Diagnosis is often delayed because a wide variety of infl ammatory and reactive lesions occur in this region in association with the teeth or dentures (Fig. 10.9). Indeed, there will often be a history of tooth extraction with subsequent failure of the socket to heal before definitive diagnosis is made. Another common story is that of sudden difficulty in wearing dentures. Regional nodal metastasis is common at presentation, varying from 30 to 84%, although false-positive and false-negative clinical findings are common.
Fig. 10.8 Cancer arising in the fl oor of the mouth. Fig. 10.9 Gingival carcinoma is often initially misdiagnosed as periodontal infection, as in this case.
CLINICAL PRESENTATION AND DIAGNOSIS OF ORAL CANCER
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The buccal mucosa (Fig. 10.10)
The buccal mucosa extends from the upper alveolar ridge down to the lower alveolar ridge and from the commissure anteriorly to the mandibular ramus and retromolar region posteriorly. Squamous cell carcinomas mostly arise either at the commissure or along the occlusal plane to the retromolar area, most being situated posteriorly. Exophytic, ulcerative and verrucous types occur. Tumours are subject to occlusal trauma, with consequent early ulceration, and often become secondarily infected. The onset of the disease may be insidious, the patient sometimes presenting with trismus due to deep neoplastic infil-tration into the buccinator muscle. Extension posteriorly involves the anterior pillar of the fauces and soft palate, with consequent worsening of the prognosis.
Infiltrating lesions will often involve the overlying skin of the cheek, resulting in multiple sinuses. Lymph node spread is to the submental, submandibular, parotid and lateral pharyngeal nodes.
Verrucous carcinoma occurs as a superficial pro-liferative exophytic lesion with minimal deep invasion and induration. Often the lesion is densely keratinized and presents as a soft white velvety area mimicking benign hyperplasia. Lymph node metastasis is late and the tumour behaves as a low-grade, squamous cell carcinoma.
The hard palate, maxillary alveolar ridge and fl oor of antrum (Figs. 10.11, 10.12)
These three sites are anatomically distinct, but a carcinoma arising from one site soon involves the others. Consequently it can be difficult to determine the precise site of origin. Except in countries where reverse smoking is practised, cancer of the palate is relatively uncommon. Most squamous cancers in this site arise in the antrum and later ulcerate through to involve the hard palate (see Ch. 15, p. 225.). The majority of malignant tumours arising from the palatal mucosa are of minor salivary gland Fig. 10.10 Buccal carcinoma arising in an area of pre-existing
leukoplakia.
Fig. 10.11 Extensive carcinoma affecting the entire hard and soft palate.
Fig. 10.12 This patient with an antral carcinoma first attended his dental practitioner complaining of loosening of the teeth, which were then extracted. Carcinoma can be seen growing through the sockets from above.
137 137 origin. Palatal cancers usually present as sessile
swellings, which ulcerate relatively late. In contrast to mandibular alveolar tumours, deep infiltration into the underlying bone is uncommon.
Carcinomas arising in the fl oor of the maxillary antrum often present as palatal tumours. Although an extensive antral carcinoma is difficult to miss, the early symptoms are non-specific and may mimic chronic sinusitis. Patients with tumours of the lower half of the antrum complain of ‘dental’ symptoms because of early alveolar invasion. The most common features are pain, swelling or numbness of the face.
Later symptoms of unilateral nasal obstruction, discharge or bleeding and dental symptoms such as painful or loose teeth, ill-fitting dentures, oroantral fistula or failure of an extraction socket to heal may follow. Lymph node metastasis from carcinomas of the palate and fl oor of the antrum occurs late but carries a poor prognosis.
DIAGNOSIS
The diagnosis of intraoral carcinoma is primarily clinical, and a high index of suspicion is necessary for all those clinicians seeing and treating patients with oral symptoms. A careful and detailed history, with particular attention to recording the dates of the onset of particular signs and symptoms, must precede the clinical examination. All areas of the oral mucosa should be carefully inspected and any suspicious lesion palpated for texture, tethering to adjacent structures and induration of underlying tissue. Any ulcer persisting for more than 2 weeks, any induration or spontaneous bleeding (particularly in a patient over 50 years who smokes and/or drinks alcohol) requires urgent referral for expert opinion.
Dental practitioners should make a full mucosal examination of the mouth and oropharynx part of their routine ‘dental inspection’.
INVESTIGATION
Surgical biopsy
A clinical diagnosis of oral cancer should always be confirmed histologically (see Ch. 8), but this should not be undertaken in general dental practice, because a biopsy will alter the appearance of the lesion and
make it more difficult for the hospital specialist to assess the tumour. The general dental practitioner should refer the patient with a suspicious lesion immediately to an oral and maxillofacial surgeon.
Within the oral cavity a surgical biopsy can usually be obtained using local anaesthesia: incisional biopsy is recommended in all cases. Whenever possible the patient should be seen at a combined clinic by a surgeon and radiotherapist before even the biopsy is carried out but, provided careful records are made, an initial incisional biopsy is acceptable—and may indeed save time in the planning and initiation of subsequent therapy. The biopsy should include the most suspicious area of the lesion and some normal adjacent mucosa. Areas of necrosis or gross infection should be avoided as they may confuse the diagnosis.
Fine-needle aspiration biopsy
This technique (see Ch. 8), which is often used in hospital, is applicable mainly to lumps in the neck, especially suspicious lymph nodes in a patient with a known primary carcinoma. It consists of the percutaneous puncture of the mass with a fine needle and aspiration of material for cytological examination. The method of aspiration needs no specialized equipment (although devices to enable controlled and prolonged traction on the plunger of the syringe may make it much simpler) and is fast, almost painless and without complications. The accuracy can be improved by using ultrasound to guide the needle into the suspicious mass.
Radiography
Plain radiography is of limited value in the inves-tigation of oral cancer. Only in very advanced lesions involving bone will changes be visible on conventional radiographs: at least 50% of the calcified component of bone must be lost before any radiographic change is apparent. Furthermore, the facial bones are of such a complexity that confusion from overlying structures makes radiographic diagnosis more difficult. However, rotational pantomography of the jaws can be helpful in assessing alveolar and antral involvement provided that the above limitations are understood.
INVESTIGATION
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Computed tomography and magnetic resonance imaging
The increasing availability of computed tomography (CT) scanning and magnetic resonance imaging (MRI) has been of great benefit in the investigation of head and neck tumours. For the evaluation of antral tumours, particularly assessment of the pterygoid regions, CT and MRI have superseded plain radio-graphy and conventional tomoradio-graphy. CT is also of value in the investigation of metastatic disease in the lungs, liver and skeleton. Positron emission tomography (PET) scan-ning is a newer modality which relies on the fact that tumours have a higher rate of metabolism of glucose. A radioactive glucose analogue is injected.
This is taken up selectively by the tumour and sub-sequently imaged.
Ultrasonography
Abdominal ultrasound is probably as accurate as CT scanning in detecting liver metastases. It is non-invasive, readily available and cost effective, and is probably the most appropriate technique for assessing the liver.