Health Tips

Oral Cancer:

* Oral cancer is increasing.
* Tobacco and alcohol are the most common aetiological factors.
* Surgery and radiotherapy are the main treatments.

Abstract

This series provides an overview of current thinking in the more relevant areas of oral medicine for primary care practitioners, written by the authors while they were holding the Presidencies of the European Association for Oral Medicine and the British Society for Oral Medicine, respectively. A book containing additional material will be published. The series gives the detail necessary to assist the primary dental clinical team caring for patients with oral complaints that may be seen in general dental practice. Space precludes inclusion of illustrations of uncommon or rare disorders, or discussion of disorders affecting the hard tissues. Approaching the subject mainly by the symptomatic approach — as it largely relates to the presenting complaint — was considered to be a more helpful approach for GDPs rather than taking a diagnostic category approach. The clinical aspects of the relevant disorders are discussed, including a brief overview of the aetiology, detail on the clinical features and how the diagnosis is made. Guidance on management and when to refer is also provided, along with relevant websites which offer further detail.
Oral cancer
Oral cancer is the most common malignant epithelial neoplasm affecting the mouth. More than 90% is oral squamous cell carcinoma (OSCC) (Table 1). Oral squamous cell carcinoma (OSCC) is among the 10 most common cancers worldwide. The mortality rate in the UK is just over 50%, despite treatment, with about 1,700 deaths per year, mainly because of late detection. The number of new mouth (oral) and oropharyngeal cancers is currently estimated to be 300,000 cases worldwide, amounting to around 3% of total cancers. In the UK, the total number of recorded cases of oral cancer is about 4,500, with around 1,700 deaths, and the incidence appears to be rising in the UK and many other countries. In the UK, there was a 17% increase in cases of oral cancer from 3,673 in 1995 to 4,304 in 1999. Scotland has about double the incidence rate of oral cancer compared with England.

Table 1. Oral malignant neoplasms
Common
Oral squamous cell carcinoma
Cancers of the oral cavity are classified according to site:
lip (International Classification of Diseases (ICD) 140),
tongue (ICD 141),
gum (ICD 143),
floor of the mouth (ICD 144) and
unspecified parts of the mouth (ICD 145)
Less common
Kaposi's sarcoma
Lymphoma
Malignant melanoma
Maxillary antral carcinoma (or other neoplasms)
Metastatic neoplasms (breast, lung, kidney, stomach, liver)
Neoplasms of bone and connective tissue
Odontogenic tumours
Salivary gland tumours
OSCC is seen predominantly in males but the male:female differential is decreasing. OSCC is seen predominantly in the elderly but is increasing in younger adults.

Potentially Malignant States
Some potentially malignant (precancerous) lesions which can progress to OSCC include the following (Table 2):


Erythroplasia Tobacco/alcohol Flat red plaque
Leukoplakia Tobacco/alcohol White or speckled
plaque
Proliferative verrucous leukoplakia Tobacco/alcohol/ human papillomavirus White or speckled or nodular plaque
Sublingual keratosis Tobacco/alcohol White plaque
Actinic cheilitis Sunlight White plaque/erosions
Lichen planus Idiopathic White
plaque/erosions/red
lesions
Submucous fibrosis Areca nut Immobile mucosa
Discoid lupus erythematosus Idiopathic White plaque/erosions/red lesions
Chronic candidosis Candida albicans White or speckled plaque
Syphilitic leukoplakia Syphilis White plaque
Atypia in immunocompromised patients HPV White or speckled plaque
Dyskeratosis congenita Genetic White plaques
Paterson-Kelly syndrome (sideropenic dysphagia; Plummer-Vinson syndrome)
Iron deficiency Post-cricoid web
* Erythroplasia (erythroplakia; see article 6) — this is the lesion most likely to progress to carcinoma, and is very dangerous.
* Leukoplakias (See article 5), particularly:

* Nodular leukoplakia
* Speckled leukoplakia
* Proliferative verrucous leukoplakia
* Sublingual leukoplakia
* Candidal leukoplakia
* Syphilitic leukoplakia.

Some other potentially malignant (precancerous) conditions include:

* Actinic cheilitis (mainly seen on the lower lip)
* Lichen planus (mainly the non-reticular or erosive type)
* Submucous fibrosis (seen in users of areca nut)
* Rarities such as:

* Dyskeratosis congenita
* Discoid lupus erythematosus
* Paterson-Kelly syndrome (sideropenic dysphagia; Plummer-Vinson syndrome).
Predisposing factors (risk factors)
OSCC is most common in older males, in lower socioeconomic groups and in ethnic minority groups.

OSCC arises because of damage to DNA (mutations) which can arise spontaneously — probably because of free radical damage, or can be caused by chemical mutagens (carcinogens), ionising radiation or micro-organisms. OSCC arises as a consequence of multiple molecular events causing genetic damage affecting many chromosomes and genes, and leading to DNA changes. The accumulation of genetic changes leads to cell dysregulation to the extent that growth becomes autonomous and invasive mechanisms develop — this is carcinoma (Fig. 1).
Actinic radiation may predispose to lip cancer but the hazards from other types of radiation are unclear.

Intraoral squamous cell carcinoma (SCC) is seen especially in relation to various lifestyle habits. These are mainly tobacco and alcohol related.

Tobacco, whether smoked or chewed, releases a complex mixture of at least 50 compounds including polycyclic aromatic hydrocarbons such as benzpyrene, nitrosamines, aldehydes and aromatic amines which are carcinogens.

Alcohol (ethanol) is metabolised to acetaldehyde, which may be carcinogenic. Nitrosamine and urethane contaminants may also be found in some alcoholic drinks. Alcohol damage to the liver might, by impairing carcinogen metabolism, also play a role.

The combination of tobacco use and alcohol consumption is particularly implicated in OSCC.

Betel quid, often containing betel vine leaf, betel (areca) nut, catechu, and slaked lime together with tobacco, and appears to be carcinogenic. Some 20% of the world's population use betel. In persons from the developing world, OSCC is seen especially in tobacco or alcohol users and particularly in betel quid users. Various other chewing habits, usually containing tobacco, are used in different cultures (eg Qat. Shammah. Toombak).
Other factors

Not all tobacco/alcohol users develop cancer, and similarly not all patients with cancer have these habits, and thus other factors must also play a part. These may include:

* Deficiencies of vitamins A, E or C or possibly trace elements
* An impaired ability to metabolise carcinogens
* An impaired ability to repair DNA damaged by mutagens
* Immune defects. These may predispose to OSCC, especially lip cancer, which is increased in, eg immunosuppressed organ transplant recipients.