Oral problems associated with chemotherapy and radiotherapy
by Dr. David H. Felix, BDS (Glasgow), MB ChB Edinburgh), FDSRCS (England), FDSRCPS (Glasgow), FDSRCS (Edinburgh)
Dr. Felix is a Consultant in Oral Medicine at Glasgow Dental Hospital and School and is also Associate Postgraduate Dental Dean for Scotland.
The number of patients immunocompromised by disease or treatment has increased dramatically in recent years largely as a result of more aggressive cytotoxic chemotherapy regimens and an improved knowledge of intensive care and management of serious infections. Complications of treatment are common. However, appropriate and timely intervention can minimise the risk of side-effects and consequently improve quality of life. At the time of diagnosis your specialist oncologist may recommend pre-treatment of your mouth to identify any existing problems which could cause complications in the future. This is particularly true in patients receiving radiotherapy as part of their overall treatment.
A wide variety of mouth problems may occur in patients receiving radiotherapy and chemotherapy. These problems can be divided into four broad categories as follows:
1. Infections (Fungal, viral and bacterial)
2. Dry mouth (xerostomia)
3. Altered taste
4. Mucositis
1. Infections
The healthy person, whose immune system functions normally, carries a large number of micro-organisms in the mouth. These organisms are called commensals and do not normally cause disease. However, they may cause problems if the patient's immune system does not function properly, as occurs in patients receiving chemotherapy, or if the local defence mechanisms in the mouth are reduced by the effects of radiotherapy. Thus oral infections are common among immunocompromised people (arising when the immune system is weakened). As many as 40% of patients receiving chemotherapy or radiotherapy may experience acute or chronic oral complications associated with their treatment.
Micro-organisms in the mouth can be divided into three broad categories: fungi (yeasts), viruses and bacteria. Organisms from each group can cause disease in immunosuppressed patients (a condition of reduced immune response) and common examples will be discussed in turn.
(i) Fungal infections
Superficial fungal infections are very common among immunosuppressed patients. Oral candidosis (commonly known as "thrush") is by far the commonest infection of any significance. The presentation of this particular type of infection varies considerably. A proportion of patients with the condition have some discomfort with white plaques adhering to the lining of the mouth. If these plaques are removed, by gentle scraping, the lining of the mouth is generally red and inflamed and there may be associated ulceration. In addition oral candidosis may appear as diffuse redness or erythema of the lining of the mouth which may be quite difficult to detect. Often there may be complete lack of symptoms and the presence of the infection may simply be detected when your doctor or dentist examines your mouth. Candidosis can also cause sores at the corners of the mouth (angular cheilitis) which are often incorrectly diagnosed and treated as cold sores.
Because oral candidosis is so common in immunocompromised patients many authorities advocate giving drugs which aim to prevent the infection rather than treating only when signs and/or symptoms develop. A variety of different drugs are available to prevent and treat this common infection. In general it responds to the use of topical drugs such as nystatin or amphotericin. Topical drugs are available as drops, creams, lozenges and suspensions and only work when the drug is in contact with the lining of the mouth. They are not effective when swallowed. A major disadvantage of topical agents is that some patients give up treatment because of the poor taste and nausea often produced by these preparations. Relapses are increasingly seen and there is now a trend towards using systemic agents (which can be swallowed) such as fluconzaole ('Diflucan') or itraconazole ('Sporanox').
(ii) Viral infections
The commonest viral infection occurring in immunosuppressed patients is caused by the herpes simplex virus. The virus causes cold sores. By the age of 16 most people have been exposed to this particular virus. It remains dormant in the body in a proportion of them. The virus can be reactivated by chemotherapy and serious local and systemic infections can occur. Extensive ulceration of the mouth can occur, with involvement of the skin around the lips. Typically this is very painful and may be associated with fever and not surprisingly difficulty in eating, as swallowing is painful.
Herpes simplex virus infections occur in 50-75% of immuno-compromised patients, therefore prevention is often offered to patients. The drug aciclovir ('Zovirax') is currently the most reliable therapy. If a patient develops a herpes infection, pain control is clearly important. The use of a local anaesthetic spray often provides some relief. In addition it is important to prevent secondary infection and an antiseptic mouthwash such as chlorhexidine ('Corsodyl') is useful.
Several other, less common, viral infections may occur in immunosuppressed patients. These include shingles which generally responds to treatment with aciclovir. More recently another virus (cytomegalovirus) has been recognised as being a cause of chronic and painful oral ulcers. In general aciclovir is not reliably effective against this virus, but it often responds to treatment with an alternative drug (ganciclovir). As a result of potential side effects, this tends to be reserved for severe infections only.
(iii) Bacterial infections
A wide variety of bacteria can be present in the mouth as commensal organisms. In immunosuppressed patients these may give rise to oral infections. In some cases, as a result of ulceration of the lining of the mouth, this may allow these organisms to gain access to the bloodstream and contribute to the development of septicaemia.
Some patients receiving chemotherapy may experience an acute flare up of pre-existing gum disease. This is believed to be a result of a change in the proportions of different bacteria in the mouth.
Some centres try to reduce the number of bacteria in the mouth by the use of antibiotics or antiseptic mouthwashes such as chlorhexidine ('Corsodyl').
Control of dental plaque is of great importance in reducing the risk of developing acute gum conditions while undergoing chemotherapy. Conventional tooth brushing may cause bleeding and once again chlorhexidine mouthwashes can help to keep the mouth clean and prevent the build up of plaque. If patients do use toothbrushes SOFT ones should be used gently.
A recent study has investigated the role of dental treatment prior to commencing chemotherapy. This has shown that the incidence of severe, life threatening infections was reduced in patients who had necessary dental treatment undertaken before starting chemotherapy. Dental treatment should be avoided during chemotherapy unless it is essential.
2. Dry mouth (xerostomia)
A dry mouth is a common problem among patients who have received radiotherapy to the head and neck region and may also occur in patients receiving chemotherapy. Unfortunately, as well as destroying malignant cells, radiotherapy causes damage to the salivary gland which is then unable to produce adequate amounts of saliva. The dryness is at its most severe during treatment with radiotherapy and is frequently permanent. The reduction in secretion of saliva results in patients with natural teeth becoming prone to develop decay on the smooth surfaces of the teeth adjacent to the gum margin. Patients who wear dentures may experience difficulty tolerating dentures due to the loss of the lubricant effect of saliva. In patients receiving chemotherapy the dryness usually improves after about two months.
Saliva has several important functions:-
Thus, it is perhaps not surprising that numerous problems can occur in patients who are unable to produce adequate amounts of saliva.
The symptoms of a dry mouth include:
These may all have a significant effect on the quality of life. The increased risk of dental decay and gum disease in patients who have a dry mouth makes it very important to consult your dentist about the best methods of keeping your teeth and gums healthy. Reducing your intake of sugar is helpful in this respect.
Relief of the symptoms of a dry mouth can be tackled by two approaches:
Salivary substitutes
Some patients find taking frequent sips of water helps. Several salivary substitutes are available commercially. Patients with natural teeth should use a preparation which contains fluoride.
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These both contain fluoride and are suitable for patients with natural teeth |
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This is an acidic preparation and is unsuitable for patients with natural teeth as it will cause a degree of erosion. |
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Comprises a gel, toothpaste and mouthwash containing lactoperoxidase |
Stimulation of additional salivary flow
Stimulation of saliva flow can be achieved by a variety of methods. Some patients control their symptoms by the use of sugarless chewing gum or sugar-free sweets. Some people advocate the use of solutions containing lemon juice or citric acid but these may result in the erosion of the teeth and should therefore be used with caution by patients who have natural teeth. In recent years a few studies have shown that a new type of drug (pilocarpine or 'Salagen') may be useful in stimulating the salivary glands to produce more saliva. Unfortunately this type of treatment may have side-effects and therefore is not used universally. Your doctor will be able to advise if this type of treatment is appropriate for you.
3. Alteration in taste
After radiotherapy or chemotherapy some patients report that their sense of taste has been altered, or indeed they may feel that they have completely lost the sense of taste. In some patients this problem resolves in time. There are several factors which may contribute to this problem, including an alteration in the balance of micro-organisms in the mouth or oral infections such as candidosis (thrush). Dryness of the mouth may also contribute to the problem, as saliva is required for the appreciation of taste. Elimination of oral infections and symptomatic treatment of xerostomia as described above may improve the situation. In some patients, deficiency of the trace element zinc may be a cause, and a course of zinc supplements may be helpful in resolving the problem.
Patients receiving chemotherapy or radiotherapy may experience a variety of problems affecting the mouth. Many specialist oncology units have links with dental hospitals where specialists with a particular interest and expertise in the management of these problems are available and willing to advise. If in doubt ask your doctor.
This is characterised by generalised inflammation and ulceration of the mouth. This is an unpleasant complication but fortunately only lasts for a limited period. A variety of treatments have been used in an attempt to minimise this particular side effect but the results are unpredictable and at present evidence is lacking to show any significant benefit. Most treatments tend to be used to reduce the symptoms. 'Difflam Oral Rinse' can be used to reduce the painful effects in mild cases whereas a local anaesthetic mouthwash can be used for more severe cases. Chlorhexidine ('Corsodyl') mouthwash can also be used to reduce the symptoms of mucositis. Use of a soft toothbrush may be helpful in keeping the mouth clean. If tooth brushing becomes too painful then chlorhexidine mouthwash can be used as an alternative. Some patients find the use of ice chips helpful in reducing the discomfort associated with this complication.
· Many oncology units have links with specialist units in Dental hospitals