Brain cancer: Understanding late effects of radiotherapy
Late side effects may happen a few months or years after treatment. They might happen once, carry on for a long time or come and go. Sometimes they cannot be cured, but it might be possible to manage them. or reduce their impact.
You might have late effects not listed here, because everyone is different. They may also be caused by a different part of your cancer treatment. It is not possible to predict if you will get them and when they might happen, which can be difficult to come to terms with. Research and support for late effects of radiotherapy is growing.
Joining a support group can be a positive way to share your experiences, feel less alone, and come to terms with the physical and emotional impact of treatment. Ask your clinical team if you need more support or want to talk about your late effects.
This page looks at late side effects.
How likely am I to get late side effects?
Before treatment you will discuss and sign a consent form with your clinical oncologist or therapeutic radiographer. They will tell you what to expect, and you can ask questions and discuss any concerns you have about late effects. It’s important to know what you are consenting to and can help to take someone with you.
You can read different radiotherapy consent forms (HERE) based on the specific area being treated. These consent forms are packed with useful information about early and late side effects.(1)
When you consent to treatment by signing the consent form, you are confirming you understand there is a chance of getting late side effects. Your team will use words like Expected, Common, Less Common and Rare.
This table shows what these words mean.
| Wording on the consent form | % chance of side or late effect | How many patients will get this? |
| Expected | 50 to 100% | Between half and all patients |
| Common | 10 to 50% | Up to half of all patients |
| Less common | Less than 10% | Fewer than one in ten patients |
| Rare | Less than 1% | Fewer than one in 100 patients |
Possible late side effects
- Somnolence syndrome: Some people might feel very tired, irritable, have headaches, sickness and lose their appetite (not feel like eating). This can happen 1 to 6 months after treatment but usually goes away after a few weeks. Medicines can help if needed.
- Problems with thinking and memory: Sometimes, people might have trouble thinking clearly or remembering things. which may be progressive and worsen with time. This can also happen after surgery or chemotherapy.
- Permanent hair thinning or loss: You may have long-term hair loss.
- Worsening or onset of seizures (epilepsy): You may need long-term treatment with anti-seizure medication.
- Changes to balance: You may have some dizziness and less co-ordination.
Rare or less common late effects
- Brain tissue damage: High doses of radiation can cause brain tissue to change permanently after treatment (radionecrosis). This may require treatment like steroids or surgery.
- Second Cancer: There is a very small chance that you could develop another type of cancer. This is rare, and depends on lots of different factors like age, area treated and radiation dose.
- Brain, brainstem or spinal cord injury: This can lead to permanent disability.
- Strokes: This is rare, but your chance of having a stroke or or mini stroke is higher.
- Stroke-like migraine attacks (SMART) syndrome: This is a rare and delayed late effect.
Side effects related to the area being treated
Ask your treatment team if you are at risk of developing the following side effects.
- Changes to pituitary hormone function: This can mean low hormone levels (hypopituitarism) and cause symptoms. You might need medical treatment such as long-term hormone replacement.
- Eye problems: Other changes to the eye might cause vision loss or dryness in the eye. These can be permanent.
- Development of cataracts: This is clouding in the lens of the eye and might need surgery to fix.
- Hearing problems: Over time, you might slowly lose your hearing or get ringing in your ears. Hearing aids can help if this happens.
What can help with these late effects?
- Keeping active: Gentle movement can help you feel better, both during and after treatment. Your treatment team can tell you what is safe for you.
- Eye care: Regular check-ups with an eye doctor (opthalmologist) and treating other health problems like diabetes can help protect your vision. If you get a cataract, surgery can fix it.
- Hearing care: Hearing aids can help if you have hearing loss caused by treatment.
- Hormone replacement: If your pituitary gland is affected, hormone medicines can help.
- Managing cancer-related fatigue: Food and drink, keeping active, keeping a fatigue diary, medicine like steroids and physiotherapy may all be options for managing fatigue. Speak to your doctor or medical team for advice; and learn more about managing cancer-related fatigue.
- Monitoring rare side effects: Talk to your treatment team as soon as you notice any changes, this can help catch and treat any serious problems early.
- Drinking fluids: Drinking plenty of fluids such as water and squash can help with fatigue and tiredness caused by your treatment. You can try diluted juice if you don’t like water.
- Skin care: The skin in the treatment area will always be more sensitive to the sun. Always protect it by covering up and use a high factor sunblock.
- Alcohol use: Please follow the NHS guidelines on safe drinking levels and any instructions you get from your team on what is right for you, your diagnosis and your treatment. If in doubt, please ask your team.
- Stop smoking: If you are looking to stop or reduce smoking, there are services available to help you.
Always talk to your doctor or treatment team about any late effects you have. Even if they are not mentioned here. Everyone is different and experiences treatment differently. There may be ways they can help you reduce or manage symptoms.
Further information
Understanding Gamma Knife radiotherapy (VIDEO SERIES) • Radiotherapy UK
Support for patients and families • Radiotherapy UK
