Radiotherapy for cancer of unknown primary (CUP)
Radiotherapy treats cancer by using high-energy x-rays to destroy cancer cells, while doing as little harm as possible to normal cells. It can help to shrink and control the cancer and relieve symptoms.
Radiotherapy to control the cancer
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If the cancer hasn’t spread too far from where it started or is in one area of lymph nodes, such as the neck, armpit or groin, you may have radiotherapy to try to cure the CUP. It may be given on its own or alongside other treatment, such as surgery. You’ll usually have this type of radiotherapy over a few weeks.
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Radiotherapy given to relieve symptoms is called palliative radiotherapy. It’s usually given as a shorter course of treatment that’s less likely to cause side effects. Palliative radiotherapy can be used to treat the following symptoms:
Pain – Radiotherapy shrinks the cancer and relieves the pressure that’s causing the pain. It may take a few weeks before you feel the full effect of treatment, so it’s important to carry on taking the painkillers prescribed by your doctor.
Breathlessness – Radiotherapy may be given to relieve breathlessness if the cancer is affecting your lungs.
Difficulty swallowing – Radiotherapy can help make swallowing easier by shrinking a cancer that’s pressing on the gullet (oesophagus).
Bleeding – Radiotherapy may help to stop or reduce bleeding that’s caused by a cancer in the bowel, cervix or womb.
Brain swelling – Radiotherapy can be used to treat a secondary cancer in the brain. It reduces swelling and helps to relieve symptoms.
How radiotherapy is given
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Radiotherapy is given in the hospital radiotherapy department. The way it’s given will depend on your situation. If you’re having palliative radiotherapy, sometimes a single treatment is all that’s needed. Or you may have a course of treatment given as a series of short daily sessions. Each treatment takes 10-15 minutes. A course of treatment is usually given daily Monday-Friday with a rest at the weekend. Your doctor will discuss the treatment and possible side effects with you.
Radiotherapy has to be carefully planned to make sure it’s as effective as possible. It is planned by a cancer specialist (clinical oncologist) and it may take a few visits.
On your first visit to the radiotherapy department, you’ll have a CT scan or lie under a machine called a simulator, which takes x-rays of the area to be treated. Marks are usually drawn on your skin to help the radiographer (who gives you your treatment) position you accurately and to show where the rays will be directed. These marks must stay visible during your treatment and permanent marks (like tiny tattoos) may be used. These are very small and are only done with your permission. You may feel a little discomfort while they’re being made.
At the beginning of each session of radiotherapy, the radiographer will position you carefully on the couch and make sure you’re comfortable. During your treatment you’ll be alone in the room, but you can talk to the radiographer who will watch you from the next room. Radiotherapy is not painful, but you have to lie still for a few minutes during the treatment.
External radiotherapy doesn’t make you radioactive and it’s perfectly safe for you to be with other people, including children, after your treatment.
Dr Vincent Khoo explains what to expect if you have radiotherapy treatment.
When radiotherapy is given to relieve symptoms (palliative radiotherapy), the side effects are usually mild. If you’re having radiotherapy to control the cancer, the side effects will depend on the dose and the area being treated.
Our section on radiotherapy has more information about side effects.
You may feel very tired during treatment and this can continue for weeks after it’s finished.
Make sure you get plenty of rest, especially if you have to travel far for your treatment. Try to balance rest with some gentle exercise. Even short walks can help to increase your energy levels and keep your muscles working.
You may notice skin changes, like sunburn, in the area being treated, or if you’re dark-skinned your skin may get darker. Avoid using perfumed soaps and creams on your skin during your treatment. The radiographers or your nurse will give you specific advice about how to look after your skin.
Side effects of treatment in different areas of the body
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Other side effects will depend on the area of the body being treated:
Stomach and pelvis (lower tummy area)
Radiotherapy to this area may make you feel sick or cause diarrhoea. Your doctor can prescribe medicines to help.
Radiotherapy to the pelvic area can also cause discomfort when you pass urine (cystitis) and a feeling of needing to pass urine more often. Drinking lots of fluids and taking mild painkillers can help.
For men, radiotherapy to the pelvis can make it more difficult to have an erection. For women it can make the vagina narrower, which can make sex uncomfortable. Even though it might feel embarrassing, it’s worth mentioning these problems to your doctor as there are often things that can help. Our sections about sexuality and pelvic radiotherapy for men and women have more information about this.
If you have radiotherapy to the chest, you may have difficulty swallowing and a cough. Your doctor can prescribe painkillers to help with this. Eating soft foods will make swallowing easier.
Head and neck
You may have a dry mouth and taste changes, a sore throat, hoarseness or difficulty swallowing. Your doctor can prescribe liquid painkillers, and eating soft foods will make swallowing easier. Your sense of taste will usually gradually return to normal when treatment finishes. Our section about mouth care has information coping with a dry mouth.
You may feel drowsy, especially towards the end of treatment. Radiotherapy to the brain also causes hair loss, but your hair will usually grow back again a few months after treatment finishes.
Tell your doctor, nurse or radiographer about any side effects you have, as there are often ways they can be reduced. Most side effects improve when your treatment finishes.