External beam radiotherapy is treatment given from a machine outside the body. The machine does not touch you. It moves around you and sends radiation to the exact area planned by your team.
This is the most common type of radiotherapy. It may be used to cure cancer, reduce the chance of it returning, or ease symptoms such as pain, bleeding, or pressure.
Common Indications for External Beam Radiotherapy
Your doctor may recommend it for:
- Breast cancer after surgery.
- Prostate cancer treatment or symptom control.
- Cervical cancer, often with chemotherapy.
- Head and neck cancers.
- Lung cancer or cancer that has spread to the chest.
- Brain tumours or cancer spread to the brain.
- Bone pain from cancer spread.
What exactly does external beam radiotherapy treat?
It treats the area included in your plan. It is local treatment, so if the target is your breast, pelvis, chest, or brain, the radiation is focused there and not on the whole body.
How should I prepare?
Attend your planning appointment and treatment sessions as scheduled. Wear comfortable clothes, and follow any instructions about bladder filling, bowel preparation, skincare, or fasting if your team gives one.
Do I need to stop taking medication?
Do not stop your regular medication unless your doctor tells you to. Bring a list of your medicines, supplements, and any previous cancer treatments to the first visit.
What happens when I arrive?
The radiotherapy radiographers will confirm your identity, check the treatment area, and position you carefully. You may lie on a flat treatment table with supports to help you stay still.
How is the treatment performed?
The team leaves the room before the radiation starts, but they can see and hear you. The machine may rotate around you. You do not feel the radiation entering the body.
How long does each session take?
Most visits take about 10 to 30 minutes. Positioning usually takes longer than the actual treatment.
Is there any discomfort?
No, the radiation itself is painless. If lying still is difficult, tell the radiographers so they can help you settle before the session starts.
Are there risks?
Side effects depend on the area treated. Skin soreness, tiredness, swallowing pain, bowel changes, bladder irritation, or hair loss in the treated area can happen. Your team should tell you which ones apply to you.
Will I be radioactive afterwards?
No. After external beam radiotherapy, you are not radioactive. You can safely be around other people.
Can I have this treatment if I am pregnant?
Pregnancy Precaution
Tell your doctor or radiotherapy team if you are pregnant or think you might be. External beam radiotherapy can harm a developing baby, so pregnancy must be discussed before treatment starts.
When will I know if it worked?
Not immediately. Some cancers shrink slowly after treatment. Your doctor will plan follow-up using symptoms, examination, blood tests, or scans when the timing is right.
When should I contact the team urgently?
Contact the team for severe or rapidly worsening symptoms, including difficulty breathing, heavy bleeding, repeated vomiting, dehydration, fever, confusion, or new weakness. The exact warning signs also depend on the body area treated, so ask for written contact instructions.
Sources and further reading
- National Cancer Institute: External Beam Radiation Therapy for Cancer
- National Cancer Institute: Radiation Therapy Side Effects
Conclusion
External beam radiotherapy is carefully planned and painless while it is being given. The biggest help you can give your team is to attend consistently and report side effects early, before they become harder to manage.