External beam radiotherapy
A cancer treatment that uses carefully aimed beams of radiation from a machine to destroy or control cancer cells, given as one or more planned sessions.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- Radiotherapy is a treatment that uses aimed radiation to destroy or control cancer cells; it is planned carefully and usually given as several small daily doses (fractions).
- The aim may be to cure the cancer (radical) or to control it and relieve symptoms (palliative); a good team is clear about which applies to you.
- Side effects depend heavily on the area treated: fatigue and a skin reaction in the treated area are common, and some effects can appear months or years later.
- It is not always the right treatment and is not a cure-all; it is usually decided by an MDT and may be combined with surgery or drug treatment.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Can destroy or shrink cancer, sometimes with the aim of cure
Radiotherapy is not appropriate for every cancer; some are better treated by surgery, drugs or active monitoring.
Side effects such as fatigue and skin reactions often build gradually. The team reviews you during treatment and helps manage symptoms.
Clear written advice on skin care and site-specific self-care.
Side effects such as fatigue and skin reactions often build gradually. The team reviews you during treatment and...
Skin reactions and many short-term effects often peak shortly after the course ends, then start to settle. Fatigue...
Many short-term effects improve. The cancer's response is assessed over weeks to months, sometimes with scans.
Late effects can occasionally appear in the treated area. Follow-up checks for response and for any late effects.
What is external beam radiotherapy?
External beam radiotherapy (EBRT) uses a machine, usually a linear accelerator, to aim beams of radiation at a cancer from outside the body. The radiation damages cancer cells so they cannot grow, while the treatment is planned to limit the dose to surrounding healthy tissue. It does not make you radioactive, and you are not a risk to others.
Radiotherapy is a treatment, not an operation. Before it starts, you have a planning session, usually a CT scan, so the team can map exactly where to aim. The total dose is usually divided into a number of smaller daily treatments called fractions. This can be a single session or a course spread over days or weeks, depending on the cancer and the aim.
The aim varies. Curative (radical) radiotherapy is given to try to get rid of the cancer, sometimes with surgery or drug treatment. Palliative radiotherapy is given to control the cancer or relieve symptoms such as pain or bleeding, when cure is not the goal. A good team is honest about which applies to you.
Radiotherapy can be very effective for many cancers, but it is not always the right treatment and is not a cure-all. It has side effects, both during treatment and sometimes long afterwards, and these depend a lot on the part of the body being treated.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Radical vs palliative radiotherapy
| Aim | What it means |
|---|---|
| Radical (curative) | Trying to get rid of the cancer; usually more sessions over weeks |
| Palliative | Controlling the cancer or easing symptoms; often fewer sessions |
| Adjuvant/neoadjuvant | Given after or before surgery to reduce the chance of the cancer coming back |
The aim and number of sessions are tailored to your cancer and your situation by the oncology team.
Preparing for your treatment
- Attend your planning (often CT) appointment, where your position and treatment area are mapped; small permanent skin marks (tiny tattoos) are sometimes used to line you up each time.
- Tell the team about all your medicines, supplements and other health conditions.
- Tell them if you are, or might be, pregnant, as radiotherapy can harm a pregnancy.
- Ask about looking after the skin in the treatment area, including washing, creams and sun protection.
- Plan for fatigue: arrange support with work, travel and daily tasks if you can.
- Ask about site-specific advice (for example diet, bladder or bowel preparation) if your treatment needs it.
- Arrange transport for the course, as daily travel over weeks can be tiring.
What happens
First you have a planning session, usually a CT scan in the treatment position. The team uses this to work out exactly where to aim the radiation and how to spread the dose, which can take a little time to prepare.
For each treatment, you lie on a couch and the machine moves around you to deliver the beams from different angles. The radiographers position you carefully, sometimes using imaging on the machine to check your position before treatment. You need to keep still, but the treatment itself is usually not painful and you feel nothing during the beam.
Each session usually takes around 10 to 30 minutes, most of which is positioning. You can normally go home straight afterwards. A course may be a single session or repeated daily (often weekdays) over weeks, depending on your plan.
Is this treatment right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- Radiotherapy is not appropriate for every cancer; some are better treated by surgery, drugs or active monitoring.
- A previously irradiated area may not be safely re-treated to a full dose because of the cumulative effect on healthy tissue.
- Pregnancy is usually a contraindication because radiation can harm the developing baby.
- Some people cannot lie still or tolerate the position needed, which must be addressed before treatment.
Delay or rearrange if…
- You are, or might be, pregnant, until this is resolved.
- You have an active infection or are acutely unwell and need stabilising first.
- Planning scans or staging information are incomplete.
- Skin in the treatment area is broken or infected and needs to settle, where it is safe to wait.
Alternatives to discuss
- Surgery, where the cancer can be removed.
- Drug treatments such as chemotherapy, hormone therapy or targeted therapy, alone or combined.
- Active monitoring (watchful waiting) for some slow-growing cancers.
- Supportive and palliative care focused on symptoms and quality of life.
- A different radiotherapy technique better suited to your cancer.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Comfort, sedation or contrast choices
If local anaesthetic, sedation, contrast or pain relief is used, ask what is planned, why, and what it means afterwards.
Benefits
- Can destroy or shrink cancer, sometimes with the aim of cure
- Can relieve symptoms such as pain, bleeding or pressure
- Can be used instead of, or alongside, surgery or drug treatment
- Often allows treatment of areas that are hard to operate on
- Usually given as an outpatient, so many people continue daily life
- Does not make you radioactive
Risks & complications
- Tiredness (fatigue) that can build during treatment and last weeks to months
- A skin reaction in the treated area: redness, darkening, soreness or itching
- Site-specific effects depending on the area treated (for example a sore mouth, swallowing problems, diarrhoea, bladder irritation, hair loss only in the treated area)
- Temporary worsening of symptoms before improvement
- More marked skin breakdown that needs treatment
- Longer-lasting effects on the treated area, such as stiffness or dryness
- Effects on fertility if the treatment area includes the reproductive organs
- Swelling (lymphoedema) near the treated area
- Permanent damage to nearby organs or tissues (depends heavily on the site)
- A second cancer developing in the treated area many years later
- Serious site-specific complications, which the team should explain for your treatment
Radiotherapy side effects depend enormously on the part of the body treated and the dose, so general lists only go so far. Ask your oncologist about the specific early and late effects for your treatment area, how likely they are, and how they are managed. Late effects can appear months or years later, so ongoing follow-up matters.
Published figures to discuss
Side-effect and outcome rates for radiotherapy vary enormously by cancer type, treatment area, total dose, fractionation and whether other treatments are used. A skin reaction and fatigue are common, while serious late effects are uncommon to rare and depend on the site. Because honest, site-specific figures should come from your oncologist for your treatment, we have not stated cure, control or complication percentages here, except to note that fatigue and a treated-area skin reaction are common and serious late effects are comparatively uncommon.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Fatigue during external-beam radiotherapy | Common | Fatigue often builds through the course and may continue for weeks after treatment. | Guide sourcesClinical context |
| Skin or mucosal reaction in the treated area | Common when skin, mouth, throat, bowel or bladder are in or near the field | The side-effect pattern depends on the treatment site, not simply on the word radiotherapy. | Guide sourcesClinical context |
| Late radiation effects | Uncommon to common depending on site, dose and nearby organs | Late effects can appear months to years later and should be discussed before treatment. | Guide sourcesClinical context |
| Second cancer caused by radiotherapy | Rare, usually a long-term risk measured over many years | For most patients the immediate cancer-control benefit is much larger than this small future risk. | NHS — Radiotherapynhs.ukSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
Radiotherapy is given over time rather than as a single event, and the effects build during and after treatment rather than the day of each session. Many people keep up daily life, but fatigue and skin or site-specific reactions often peak towards the end of a course and for a few weeks afterwards.
- Feeling increasingly tired towards the end of the course and for some weeks after
- A skin reaction in the treated area that improves over a few weeks
- Site-specific soreness (for example mouth, throat, bladder or bowel) depending on the area
- Needing rest and gentle activity rather than a quick return to full energy
Aftercare
- Follow the team's skin-care advice for the treated area, including gentle washing and sun protection.
- Pace yourself and rest as needed; light activity such as short walks can help fatigue.
- Use any prescribed creams, mouth care, anti-sickness or other medicines as directed.
- Keep eating and drinking as well as you can, with dietitian support if eating is affected.
- Attend follow-up appointments so response and any late effects are checked.
- Know who to contact for advice and what counts as an emergency.
- Skin-care products recommended by the team obtained
- Support arranged for fatigue (help at home, time off if possible)
- Transport sorted for daily sessions over the course
- Site-specific advice (diet, bladder/bowel prep) understood
- Contact number for the radiotherapy team saved
- Follow-up appointments noted
⚠ Get urgent help if…
- A high temperature, shivering or feeling very unwell, especially if you are also having chemotherapy, needs urgent contact with your team.
- Skin in the treated area that breaks down, blisters or weeps and is not settling.
- Severe or uncontrolled pain, or pain that is suddenly much worse.
- Difficulty swallowing, breathing, or passing urine or stool, depending on the treated area.
- Heavy or new bleeding.
- Severe diarrhoea, vomiting or signs of dehydration.
- Any symptom the team has specifically told you to report for your treatment area.
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
Radiotherapy can shrink or destroy cancer, and the effect usually continues to build for weeks to months after treatment finishes rather than being immediate. For curative treatment, success means controlling the cancer in the treated area; for palliative treatment, success means easing symptoms such as pain or bleeding.
No radiotherapy guarantees a cure, and a response in the treated area does not rule out cancer elsewhere. Your team will explain how and when your response will be assessed, often with examination and scans, and what the realistic aim was.
How durable the result is depends on the cancer type, stage, dose and whether other treatments were used. Some cancers are controlled long-term by radiotherapy; others may need further treatment if they recur. Late effects in the treated area can appear months or years later, which is why follow-up continues after treatment ends.
Related tests, treatments or support
Radiotherapy is often combined with surgery (before or after), with chemotherapy (chemoradiotherapy), or with hormone or targeted treatments, depending on the cancer. The MDT decides how best to sequence these. More precise delivery techniques such as IMRT, IGRT or SABR may be used to shape or target the dose where appropriate.
Follow-up & long-term care
After treatment you are followed up to assess the cancer's response and to watch for side effects, including late effects that can emerge over months or years. The interval and tests depend on your cancer. You should have a contact for questions and know what symptoms to report urgently.
- Attend follow-up appointments, which may continue for years to check for late effects and recurrence.
- Continue skin and symptom care in the treated area as advised.
- Report new or persistent symptoms in or near the treated area.
- Keep a record of the treatment area and dose for future clinicians, as it can affect later care.
Repeat, follow-on and what comes next
- Further radiotherapy, surgery or drug treatment may be needed if the cancer does not respond or recurs.
- Re-irradiating the same area is often limited by the dose healthy tissue has already received.
- The plan may be adjusted during a course based on how you respond or tolerate it.
- Late effects may need their own ongoing management.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Clear written advice on skin care and site-specific self-care.
- A named contact and emergency instructions for side effects.
- Planned follow-up to assess response and watch for late effects over time.
- Support for fatigue, nutrition and symptoms, including specialist nurse and dietitian input.
- Coordination with the wider cancer team and your GP.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- The type and number of treatment sessions (fractions) and the total dose
- The delivery technique used (for example conformal, IMRT, IGRT or SABR)
- Planning scans, imaging on the machine and treatment preparation
- Whether radiotherapy is combined with chemotherapy or surgery
- Consultant oncologist fees and physics/radiography input
- Follow-up appointments and management of side effects
- The aim of treatment and the number of sessions planned
- The technique used and why it has been chosen for you
- What planning scans and on-treatment imaging are included
- What management of side effects and follow-up is included
- How any combined chemotherapy or surgery is costed and coordinated
- What happens, and what it costs, if the plan changes or complications occur
On the NHS? External beam radiotherapy is provided on the NHS when clinically indicated; people sometimes use private care for speed or choice, but responsible private treatment coordinates with NHS cancer services.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Not being clear whether treatment is intended to cure or to relieve symptoms.
- Underplaying late effects that can appear months or years later.
- Not explaining site-specific risks (for example fertility, bowel, bladder, swallowing).
- Presenting a particular machine or technique as a cure-all.
- No written aftercare plan or emergency contact for side effects.
Marketing red flags
- Claiming a newer machine 'cures' cancer or is always better than standard radiotherapy.
- Selling advanced techniques (IMRT, IGRT, SABR) as automatically superior for every patient.
- Promising no side effects or guaranteed results.
- Discouraging MDT discussion or a second opinion.
- Offering radiotherapy for indications without good evidence or outside guidelines.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- What is the aim of my radiotherapy: to cure the cancer, or to control it and relieve symptoms?
- How many sessions will I have, and over what period?
- What are the likely short-term and long-term side effects for my treatment area?
- Is this technique the right one for me, or would another approach (or no radiotherapy) be reasonable?
- How and when will you check whether it has worked?
- Who do I contact if I have side effects, and what counts as an emergency?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my treatment, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this treatment not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Does radiotherapy make me radioactive?
Does it hurt?
How many sessions will I need?
Will I be able to work and drive?
Is newer equipment always better?
Can I have radiotherapy privately?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS — Radiotherapy NHS — Side effects of radiotherapy Cancer Research UK — External radiotherapy Macmillan Cancer Support — Radiotherapy side effects Cancer Research UK — Long term side effects of radiotherapy Royal College of Radiologists — Clinical oncology
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
Related guides: Intensity-modulated radiotherapy (IMRT) · Image-guided radiotherapy (IGRT) · Stereotactic ablative radiotherapy (SABR / SBRT) · Clinical oncology consultation · Brachytherapy (internal radiotherapy)