Radiotherapy: types, what to expect and how side effects are managed

What radiotherapy is and how it works

Radiotherapy (radiation therapy) damages the DNA of cells in the treated area. Cancer cells are less able to repair this damage and die, while most normal cells recover. The total dose is therefore usually split into many small daily doses (fractions), giving healthy tissue time to repair between sessions.

Unlike chemotherapy, which acts throughout the body, radiotherapy is a local treatment. Together with surgery and systemic drugs it is one of the three pillars of cancer treatment, and the three are often combined.

Treatment is delivered by a team: a clinical oncologist who sets the aim and dose, medical physicists who calculate the plan and check the equipment, and therapeutic radiographers who position you each day. Radiotherapy is increasingly combined with immunotherapy or targeted therapy – for example stereotactic treatment of one or two metastases in people whose cancer is otherwise well controlled by drugs. The tumour board decides on such combinations, because not every drug is safe to give at the same time as radiation.

When radiotherapy is used

• Radical (curative) – as the main treatment, for example in prostate, cervical and head and neck cancer, or early lung cancer in people who cannot have surgery.
• Adjuvant – after surgery, to destroy any remaining cancer cells; for example after breast-conserving surgery for breast cancer.
• Neoadjuvant – before surgery, to shrink the tumour (for example in rectal or oesophageal cancer).
• Chemoradiotherapy – combined with chemotherapy, which makes the radiation more effective.
• Palliative – to relieve pain from bone metastases, bleeding, or pressure on a nerve or the spinal cord; often just one to a few sessions. It is an important part of palliative care.

Types of radiotherapy

The right technique depends on the tumour type and location, not on which technology is newest. Not every cancer benefits from protons or stereotactic treatment.

What happens during treatment

Consultation and planning. A clinical oncologist (radiation oncologist) reviews your scans (CT, MRI, PET-CT) and pathology and explains the aim and likely side effects. You then have a planning CT scan in the exact position you will be treated in. Immobilisation devices – a mask for head and neck treatment or a vacuum cushion – and tiny permanent skin marks are often used.

Treatment planning. The doctor outlines the tumour and the organs to protect, and medical physicists calculate the dose distribution. This takes from a few days to around two weeks.

The sessions. The radiation itself lasts a few minutes, and you are usually in the room for 10–20 minutes. You feel nothing – no heat and no pain. A conventional course runs Monday to Friday for three to seven weeks, while modern hypofractionated and stereotactic schedules are much shorter. You will be reviewed regularly throughout.

Side effects

Side effects depend mainly on the area treated and the total dose. Most build up gradually from the second week and settle within a few weeks after treatment finishes.

• Fatigue – the most common general effect.
• Skin reactions – redness, dryness, itching and sometimes peeling in the treated area.
• Head and neck – sore throat, dry mouth, taste changes and difficulty eating.
• Chest – painful swallowing and cough; rarely, lung inflammation weeks later.
• Abdomen and pelvis – nausea, diarrhoea, passing urine more often, bladder irritation.
• Brain – hair loss in the treated area, headache, tiredness.

Late effects, appearing months or years later, are less common and depend on the area – for example tissue fibrosis, lymphoedema, a permanently dry mouth, bowel or bladder changes, and very rarely a second cancer many years later. Modern techniques have substantially reduced these risks.

Looking after yourself during treatment

• Wash the treated skin gently with lukewarm water and mild soap; do not rub it, avoid perfumed products and keep it out of the sun.
• Use only the creams your team recommends.
• Wear loose cotton clothing.
• Drink plenty and eat well to keep your weight stable – see Nutrition during cancer treatment.
• Stop smoking – it worsens side effects and can reduce how well treatment works.
• Gentle physical activity helps with fatigue.

External radiotherapy does not make you radioactive, so you can safely be around children and pregnant women. With some internal treatments using radioactive substances – such as radioactive iodine for thyroid cancer – short-term precautions apply.

When to see a doctor

Tell your radiotherapy team promptly if you develop a fever, severe pain, bleeding, broken or weeping skin, inability to swallow fluids, severe diarrhoea, breathlessness or new weakness or numbness. Also see a doctor if new symptoms appear in the treated area months after treatment – they are not always related to cancer, but they need to be assessed.

Radiotherapy abroad and in Türkiye

Large accredited hospital groups in Istanbul have modern linear accelerators, stereotactic radiosurgery, brachytherapy and, in some centres, proton therapy. Patients from Bulgaria and the rest of Europe sometimes travel for stereotactic treatment that lasts only a few days, or for a second opinion on a proposed plan. A course lasting several weeks requires a longer stay. Ask for a written plan with the dose and number of fractions, confirm who will follow you up once you are home and how late effects would be managed. Organisers such as New City Clinic coordinate the hospital, doctor, accommodation, transfers and interpreter. See also Cancer treatment in Türkiye.