Oral cancer
The survival of patients with oral cancer remains poor despite recent surgical advances. About 30-40% of patients with intra-oral cancers will survive five years; the short survival time is caused, largely, by late detection.[1] Public awareness of oral cancer as compared with other cancers is low and this contributes to delays in diagnosis.[2] However, the mouth can be examined by healthcare professionals with much greater ease and accuracy than many other parts of the body. All healthcare workers need to be aware that a patient with an ulcer or white patch that persists beyond three weeks should be referred for further evaluation to an oral physician or to an oral and maxillofacial surgeon. Tobacco use is a major cause of oral cancer, and doctors and other health professionals can contribute to primary prevention by making patients aware that tobacco, in all forms, predisposes them to oral cancer.
Methods
The majority of references in this article were obtained from a personal collection built during 10 years of work in this subject and during a study of screening for oral cancer. A Medline search of articles published between 1966 and 1998 using the terms “mouth” and “neoplasms” yielded 20664 articles. Adding the keywords “systematic” and “review” did not identify any systematic reviews. The Cochrane database does not list any protocols or completed systematic reviews of randomised controlled trials of head and neck surgery.[3] Searching the Cochrane Controlled Trials Register identified 11 randomised controlled trials, mainly on the use of chemotherapy. The American College of Physicians Journal Club and Evidence-Based Medicine database (1991-1997) lists no articles relating to mouth neoplasms.[4]
Definition and classification
Neoplasms of the mouth are defined as neoplasms involving the oral cavity, which begins at the lips and ends at the anterior pillar of the fauces. The most common intra-oral malignancy is squamous cell carcinoma. Tumours of the salivary gland have different risk factors and are relatively rare. The major types of carcinomas encountered in the mouth are shown in the box.
Epidemiology and risk factors
Oral cancer is relatively rare in the United Kingdom–2000 new cases are diagnosed each year–but this is rising, especially among men.[5] Worldwide it is estimated to be the sixth most common cancer, prevalence being highest in India.[6] An increase in incidence has also been reported in central and eastern Europe, especially among younger men.[7] Mortality remains high and although the prognosis for cancer of the lip is good, the prognosis for intra-oral squamous cell carcinoma remains poor.[5] There is good evidence that tobacco in all forms, including the tobacco in snuff and betel quid (a mixture of ingredients including betel leaf, areca nut, slaked lime, and tobacco, which is wrapped in a betel leaf and chewed), is carcinogenic in the upper aerodigestive tract, which includes the mouth.[8] There is fairly convincing evidence that alcohol is also a carcinogen and acts synergistically with tobacco.[9] There is little convincing evidence that mouthwash use, poor oral hygiene, or oral infections of viral origin play an important role in the aetiology.[10 11] Consuming fruit and vegetables may have a protective effect. It has been suggested that lichen planus and oral submucosal fibrosis are associated with an increased risk of intra-oral malignancy. Wide variations in the malignant potential of these lesions have been reported. There is a slight familial risk for oral cancer which may be related to the similar exposures to tobacco and alcohol which occur among family members.[12] Patients who have had renal transplants have a higher incidence of cancer of the lip which may be due to immunosuppression.[13]
Although a premalignant lesion (epithelial dysplasia) is recognised, many oral cancers do not go through a premalignant stage. Not all premalignant lesions become malignant, and some regress.[14] There is insufficient evidence to determine which features reliably predict malignant potential, but the degree of dysplasia may be a factor.
Prevention
Primary prevention involves stopping the use of tobacco. Regression of premalignant lesions has been reported in former smokers.[15 16] In the Indian subcontinent and in areas with large populations of Asian migrants, reducing the use of betel quid may also be beneficial. The prevalence of betel quid use remains high in immigrant populations in the United Kingdom.[17]
Early identification of premalignant lesions and small oral cancers will allow patients to be treated earlier. Screening for oral cancer is simple. It does not require any laboratory support; at the most it requires a good light source. Mass screening in the United Kingdom is not recommended because it does not fulfil the principles for screening suggested by Wilson and Jungner.[18 19] However, dentists should be encouraged to screen patients opportunistically especially if patients are males, smokers, and over 40 years old.
Public campaigns are necessary, however, to make patients aware of oral cancer; patients often delay seeking professional advice for over three months.[20 21] The 1992 US National Health Interview Survey showed that the 15% of adults who had had an oral examination were likely to be better educated about and more aware of the risks of oral cancer than those who had not had such an examination.[22]
Clinical features
Oral squamous cell carcinoma presents in a variety of ways but most early lesions are asymptomatic. Premalignant and early malignant lesions may present as painless white or red patches. Lesions that look speckled–that is, non-homogeneous–or those that exhibit erythroplasia are more likely to have evidence of severe dysplasia on histological examination than homogeneous white patches. Some malignant lesions present as small, indolent ulcers. Many premalignant lesions regress if tobacco use is stopped. Lesions of intermediate malignancy may present as persistent ulceration with fixation to underlying tissues and regional lymph node enlargement. Late stage oral malignancy may result not only in large, indurated, crater-like ulcers with rolled margins but also in bony destruction, leading to mobile teeth, loss of teeth, or even pathological fractures. These may be associated with pain, numbness, or paraesthesia.
Figure 1 shows a white homogeneous patch in the floor of the mouth of a smoker. A biopsy of this showed mild epithelial dysplasia. Figure 2 shows a speckled white patch in the buccal mucosa of a male smoker. Figure 3 shows an erythematous lesion on the lower alveolus near the wisdom tooth area. Biopsies of the lesions in figures 2 and 3 confirmed the presence of squamous cell carcinoma. Figure 4 shows a typical late stage squamous cell carcinoma.
[Figures 1-4 ILLUSTRATION OMITTED]
Details of how rarer types of cancers present are shown in the table.
Rarer types of oral cancer Type of turnout Principal site Principal presentation Salivary gland Palate, floor of mouth Soft lumps Melanoma Palate, gingiva Brown or black patches Lymphoma Tongue, palate, gingiva Rapidly growing ulcer Leukaemia Gingiva, whole mouth Enlargement, redness, Candidiasis
Investigations
The most useful investigations for suspected oral malignancy are representative biopsies, which may be taken from more than one area. These are usually done under local anaesthesia but occasionally an examination under general anaesthesia is useful. Intra-oral radiographs, orthopantomograms (radiographs of both jaws), and computed tomography scans may help define the extent of the lesion and any bony or nodal involvement.
Management
In the United Kingdom, upper aerodigestive tract neoplasms are treated by ear, nose, and throat specialists; oral and maxillofacial surgeons; plastic surgeons; and oncologists.[23] There is no systematic collection of basic data, there are few combined clinics, and the use of other support services is variable.[23]
Treatment for oral cancer is principally surgical. Few patients are treated solely with radiotherapy and even fewer with chemotherapy. Radiotherapy and chemotherapy are often used for adjuvant and adjunctive therapy. The factors that affect the choice of treatments for individual patients are beyond the scope of this article.
The aim of surgical management is to excise the entire lesion to eliminate possible channels of spread, such as the lymphatic system, nerves, and blood vessels. This ablative surgery is followed by reconstructive surgery which is used to improve healing and restore function and improve the patient’s quality of life. Debulking surgery is used as a palliative measure for incurable tumours. Some surgical procedures only involve soft tissues. Others involve both hard and soft tissues. The patient in figure 3, for example, had an excision of the maxillary alveolus. Neck dissection is frequently required, with a consequent increase in postoperative morbidity. Reconstruction may involve not only skin grafts and flaps, but also bony grafts and implants.
Radiotherapy is rarely used as a primary treatment; it is used either to debulk the tumour before surgery or to prevent recurrences and eliminate residual tissue after an incomplete resection. The complications of radiotherapy include oral mucositis and osteoradionecrosis, which present difficult management problems. Radiotherapy is also used if extracapsular spread is thought to have occurred; in this case, it is done within six weeks of surgery.
Chemotherapy is used nearly exclusively as a palliative treatment when there has been a local recurrence or metastases. However a meta-analysis of 42 randomised controlled trials involving 5079 patients has shown that adjuvant chemotherapy for squamous cell carcinomas of the head and neck results in a significant improvement in survival (relative hazard ratio of dying 0.89) but at the cost of a significant increase in morbidity (toxicity was increased with a relative proportion of 2.17).[24]
The principles of the treatment of oral cancer and its sequelae are well described in the specialist literature.[25] Few studies have assessed the quality of life and coping strategies of patients who have undergone surgery.[25-28]
A systematic review of the management of oral neoplasms is needed to provide the information required for patients and their medical advisers to make more informed choices about treatment.
Conclusion
The prognosis for large oral neoplasms remains poor. Healthcare professionals can make a large impact on the morbidity and mortality caused by oral cancer by referring patients with possible early or premalignant oral lesions for a specialist opinion as soon as possible. Raising public awareness of oral cancer may also assist in early diagnosis. A successful public health campaign to reduce the use of tobacco would also reduce the incidence of this condition, as has been shown in India.[16]
Main types of oral cancers
Epithelial Squamous cell Verrucous Spindle cell Adenoid squamous Basal cell Malignant melanoma Odontogenic Primary bone tumours Salivary gland tumours Mucoepidermoid Acinic cell Adenocarcinoma Haemopoietic Lymphoreticular Metastases from other sitesSummary points The incidence of squamous cell carcinoma of the oral cavity is increasing The use of tobacco, in all forms, is major risk factor for squamous cell carcinoma; tobacco acts synergistically with alcohol Squamous cell carcinoma presents intra-orally as a non-healing ulcer, or a white or red patch A biopsy done under local anaesthesia is the single most important investigation in diagnosing oral cancer Five year survival rates for cancer of the lip are good but are low for other forms of mouth cancers, especially if the lesions are large at the time of diagnosis
