External radiotherapy treats cancer by using doses of high-energy x-rays to destroy the cancer cells while doing as little harm as possible to normal cells.

The treatment is usually given every weekday in the hospital radiotherapy department, with a rest at the weekend. You may sometimes have treatment more than once a day, and occasionally you may also have treatment at the weekend.

It is important to follow the scheduled treatment plan and avoid any unnecessary gaps in your course of treatment. The treatment will usually last 3–7 weeks, depending on the type and size of the cancer. Your radiotherapy doctor (clinical oncologist) will discuss the treatment with you.

Some hospitals now use what is known as conformal radiotherapy (CRT) or intensity-modulated radiotherapy (IMRT). A special attachment to the radiotherapy machine carefully arranges the radiation beams to match the shape of the cancer.

Shaping the radiotherapy beams reduces the radiation received by healthy surrounding cells. This can reduce the side effects of the radiotherapy treatment (such as a dry mouth) and may allow higher doses to be given, which could be more effective.

To ensure that the radiotherapy is as effective as possible, it has to be carefully planned by a clinical oncologist. It is a very precise treatment and it is important that you are able to lie still, in exactly the same position, for each treatment.

To help you do this, you may need to wear a see-through Perspex or plastic device called a 'mould', 'shell' or 'mask' that helps to keep your head as still as possible. The mould allows you to see and breathe normally, but it may make some people feel claustrophobic. You will only have the mould on for a few minutes at a time, and most people soon get used to wearing it.

Your mould will be made on one of your first visits to the radiotherapy department. The radiographer (the person who gives the treatment) will explain the whole process to you before starting.

Treatment planning is a very important part of radiotherapy and several visits may be needed.

On your first visit to the radiotherapy department, you will have a CT (computerised tomography) scan taken of the area to be treated. A CT scan takes lots of images from different angles to build up a three-dimensional picture of the area. At the same time radiographers will take measurements from you which are needed for treatment planning. This session will usually take about 45–60 minutes and you will need to wear your radiotherapy mould. Sometimes you may also need to go to the hospital’s scanning department to have an MRI scan. This uses powerful magnetic fields to give a detailed picture of part of your body, which can give additional useful information.

The radiographer’s measurements and the information from the scans are fed into the radiotherapy planning computer to help your doctors plan your treatment more precisely.

Marks are drawn on the mould (or sometimes on your skin) to help the radiographer position you accurately, and to show where the rays are to be directed. If the marks are on your skin they must stay there throughout your treatment, but they can be washed off once your course of treatment is finished. Sometimes a few small permanent marks (tattoos) may be made on your skin instead of pen marks. The marks are tiny and will only be done with your permission.

At the beginning of your treatment you will be given instructions on how to look after the skin in the area being treated. You will be told whether you can wash the marked areas of skin.

Before each session of radiotherapy, the radiographers will position you carefully on the couch, with the mould fitted, and make sure that you are comfortable. During your treatment, which only takes a few minutes, you will be left alone in the room. However, you will be able to signal to the radiographers who will be watching you on a television monitor from the next room. You will have to lie still while the treatment is given, but you will not feel the radiotherapy: it is similar to having an x-ray.

External radiotherapy does not make you radioactive, and it is perfectly safe for you to be with other people, including children, throughout your treatment

Radiotherapy can cause some temporary side effects. These will gradually disappear after the treatment has finished. You may have some of those listed below:

Sore skin

The skin over your face and neck is very likely to gradually redden or darken and become sore (like sunburn). This starts after about two weeks of treatment and may last for 2–4 weeks after the treatment has finished. Sometimes the skin will peel or break. The radiotherapy team will tell you how to look after your skin. Some chemicals can make the skin more sensitive to radiation effects, so it is very important to use only soaps, creams and lotions that are recommended by the radiotherapy staff.

Rarely, the skin in the treated area may break down and become moist. The radiotherapy team can give you advice if this happens.

Sore mouth and throat

Your mouth and throat will very probably become sore and inflamed after a couple of weeks of treatment and you may develop some mouth ulcers. Your voice may also become hoarse. You may become sensitive to very strong flavours and/or extreme heat and cold. Eating food may become difficult and swallowing painful.

Your doctor can prescribe painkillers, mouthwashes and protective gels that coat the lining of the mouth, to help ease this. You will be given advice on how to change your diet to make eating more comfortable. For example, you will be encouraged to eat soft food and to avoid smoking, drinking spirits and eating hot or spicy foods. Drinking plenty of bland fluids like cool drinks (milk, water and so on) or sucking ice cubes, will help to keep your mouth moist. You will be able to discuss any problems with eating and drinking with a speech and language therapist and/or a dietitian.

Once the course of radiotherapy has finished, your mouth will gradually heal and most people get back to eating normally a few weeks after the treatment has finished. However, the effects of the radiotherapy occasionally make the throat too uncomfortable for a person to eat or drink and they may need to be fed by a nasogastric tube or a PEG tube.

Dry mouth

You may notice that you can’t produce as much saliva as before the treatment. The lining of your mouth and throat may become dry and this can make eating and speech difficult. You may also notice a feeling of sticky mucus in the throat, as sometimes radiotherapy makes the saliva thick and stringy, which can be very distressing. To reduce the dry feeling, you may find it helpful to use an artificial saliva spray, or to wipe small amounts of butter or vegetable/olive oil on the inside of your cheeks.

Before radiotherapy treatment, you may be given injections of a drug called amifostine. This drug can help to protect the salivary glands from the damage caused by the radiotherapy. The side effects of amifostine include dizziness, low blood pressure, feeling sick and chills. Amifostine is still being tested as a treatment and is not used as part of the standard treatment for head and neck cancers.

Although you may start to produce some saliva again within a few months of treatment, it is important to be aware that the problem might continue for some time. If your mouth, throat, or the upper part of your neck is being treated, your mouth may become permanently dry. See our section on coping with a dry mouth.

Dental care

If you have a dry mouth, you will need to take special care of your teeth, as they will be much more prone to tooth decay. This is because your saliva normally acts as a protective film. You should follow the dental hygiene advice that you are given, such as brushing regularly with a soft toothbrush or gauze. You will usually be asked to apply fluoride gel to your teeth every day, either as a mouth wash or in special gum shields, to help protect your teeth from decay. You will need to see your dentist regularly, because your mouth may be sensitive and easily irritated during your treatment.

If your dentist recommends that one of your teeth needs to be removed, you should be referred to a specialist oral and maxillofacial surgeon for advice and treatment.

Loss of taste

If part, or all, of your mouth is treated, then your sense of taste will quickly change during the radiotherapy. Some people either lose their sense of taste completely or find that everything tastes the same (usually rather metallic or salty, or like cardboard). Although your sense of taste will recover, it may take many months for it to return to normal after the treatment.

Loss of appetite

Some people lose their appetite as a general effect of radiotherapy. A sore, dry mouth can also make eating difficult. If you don't feel like eating, it is a good idea to supplement or replace your meals with nutritious high-calorie drinks such as Complan® or Build-up® (available on prescription). You could also try baby foods, which are soft but also high in protein and calories.

You will be able to discuss any problems with your diet with the dietitian or specialist nurse at the hospital.

We have separate information on diet and cancer, which has helpful tips on how to eat well when you have a sore or dry mouth, or have lost your taste and appetite.

Hair loss

For most people, radiotherapy for cancers of the head and neck will not make their hair fall out, or the amount of hair lost will be very slight. It is unusual to lose any hair from the scalp during radiotherapy for head and neck cancers, as hair only falls out where the x-ray beam enters and leaves your body. For most people this will be limited to parts of the face and neck. Only the hair very close to the tumour is likely to be permanently lost, so men will lose their beard permanently in those areas of skin that become red or dark and sore during treatment. Hair loss can occur when tumours around the eyes and ears are treated. Your doctor will advise you if permanent hair loss is likely in your case, and can tell you where any hair loss is likely to occur.

Tiredness

You may find that the treatment makes you feel very tired. During your treatment it is important to get as much rest as you can, especially if you have to travel a long way each day for your treatment.

Feeling sick (nausea)

This is uncommon, but your doctor can prescribe anti-sickness tablets or medicines (anti-emetics) if it is a problem. See our section on controlling nausea and vomiting.

Stiff jaw

Operations to the back of the mouth and throat can lead to stiffness of the jaw. You will be given exercises to do in order to prevent this from becoming a permanent problem. If the radiotherapy is to the back of your throat (nasopharynx), the muscles used to open and close your mouth can also become stiff.

You will be shown mouth-opening exercises that you should do at least twice a day. There are also specialist aids available to help you exercise your jaw. Your doctor, specialist dentist, or speech and language therapist can give you advice about exercises and where to buy an exercise aid.

Bad breath

This can develop during treatment and may be helped by regular mouth care and mouth washes. Your doctor or nurse will be able to advise you on how to do this effectively. Your doctor may also prescribe an antibiotic medicine that can help.

All these side effects can be upsetting and difficult at the time. However, it is helpful to remember that many are temporary and will gradually disappear.

These side effects occur especially towards the end of the course of treatment and during the first couple of weeks after your treatment has finished. The effects can be mild or more troublesome, depending on the dose of radiotherapy given and the length of your treatment. Your doctor will be able to advise you on what to expect, and can offer treatment to help to relieve the side effects.