Oral Cancer

What causes oral cancer?

While there are close associations between oral cancer and certain life-styles as well as with pre-existing health problems, there can often be no obvious predisposing factors.

Established risk factors are:

• smoking tobacco
• chewing tobacco/oral snuff/ betel quid
• heavy drinking (usually defined as drinking over 14 units per week for women and over 21 units per week for men: a unit of alcohol can be half a pint of beer or a small glass of wine or sherry or a measure of spirits).

Other possible contributory factors include:

• candida albicans (yeast fungi) infection
• viruses, notably certain human papilloma viruses
• immune deficiency diseases
• long standing dental trauma or infection
• sunlight (for cancers on the lip)
• radiation
• dietary deficiency of vitamins A,C and iron
• anaemia.

How common is it?

New cases of cancer are registered by the Government's Office of Population Censuses and surveys (OPCS) using the International

Classification of Diseases (ICD). If cancers of the lip, tongue and oro/hypo-pharynx are included (ICD 140,141, 143-146 and 148-149), about 1 per cent of cancers are 'oral'. Cancers of the oropharynx and hypopharynx have been included with other oral cancers because they have common risk factors, unlike cancers of the major salivary glands and nasopharynx.

Cancer registrations in England and Wales, 1989

As for cancers generally, most occur amongst elderly people. However, there is some evidence that oral cancer is becoming more common in women and younger patients, in the UK as in a number of other countries. Oral cancer is nearly twice as common amongst men as amongst women, which may be related to differences in risk habits between the sexes.

While the incidence of oral cancer was fairly static through most of the eighties, there are now signs of rising incidence. Cancer registration figures beyond 1989 are not yet published.

Oral cancer cases and deaths (ICD 140-149 excluding 142,147) in England and Wales

How many deaths are related to oral cancer?

About 1400 people die from oral cancer in England and Wales each year. This compares with 1339 deaths from cervical cancer in 1995.

The number of deaths caused by oral cancer is about half the number of registrations, indicating the scope for successful treatment. However, treatment is difficult and the number of deaths due to oral cancer remains unacceptably high, particularly amongst young males and in lower socio-economic groups.

Cancer deaths in England and Wales, 1992

How is oral cancer treated?

Radiotherapy and surgery are the main treatment methods. Small cancers do well with either method. Large cancers need combined treatment and often require major reconstructive surgery to replace any missing soft tissue and jaw bone. This may involve transplanting tissue from elsewhere in the body with microsurgery to join the blood vessels. Dental implants can help in the long term rehabilitation of oral cancer patients.

Where are oral cancers found?

There is increasing concern amongst dentists to ensure that dental examinations include a systematic soft tissue screening in an attempt to bring oral cancer under control.

Almost all oral malignancies are located in the soft tissues and can be detected by inspection. Often, an oral cancer is preceded for several months or even years by a visible whitish (leukoplakia) or reddish (erythroplakia) patch - pre-cancerous lesions. The examining dentist will not usually be able to make a definitive diagnosis when a cancer or pre-cancerous lesion is first seen. The patient would normally be referred for biopsy or other tests at the oral surgery or oral medicine department of a local hospital. Such hospital departments treat referrals for investigation as a very high priority, because of the need to start treatment quickly if a cancer is found.

Most oral cancers are of the type called squamous cell carcinomas and are found to occur on the side of the tongue, the floor of the mouth, the lingual sulcus (grooves at the sides of the tongue), or behind the teeth. However, cancers related to chewing tobacco and betel quid may arise in the cheek and at the junction of the lower and upper lips. Cancer of the lip usually involves the bottom lip and may be related to ultraviolet radiation (overexposure to sun light) and smoking. Rare forms of cancer such as malignant melanoma and cancer of minor salivary glands may present as oral lesions. Mouth cancers can spread into the jaws or the lymph glands in the neck.

The mouth may also be a transfer site for cancers arising in other sites, such as the lung, breast, prostate, kidney or thyroid, though these usually deposit in the jaw bones, rather than the soft tissues.

Oral cancer cases and deaths by site for England and Wales, 1991

What does a dentist do at a checkup?

Dental checkups involve an examination of the entire mouth, not just the teeth. Screening for oral cancer and potentially malignant lesions and conditions in the course of regular dental checkups is an important way of speeding up diagnosis and treatment and improving survival rates.

Never delay seeking advice on a non-healing sore or persistent lump in the mouth.

What would the British Dental Association like to see?

• Reintroduction of free dental examinations under the National Health Service would aid the early detection of oral cancer.
• The Department of Health's 'Health of the Nation' programme has set targets for reducing cancer incidence and improving death rates but an oral cancer target is not included. For skin cancer (including melanoma), which causes approximately 1700 deaths per year in England and Wales, the target is to halt the year-on-year increase in incidence by the year 2005. The British Dental Association has proposed that the same target should be set for oral cancer with a coordinated national programme of education in early identification of high risk individuals and suspect lesions for dentists.

The BDA also wants to see a coordinated campaign to raise public awareness of oral cancer and its risk factors. The Health Education Authority will be making a start on this early in 1996, in collaboration with the BDA.