How does radiotherapy work?

Treatment is planned around the tumour’s position, size and nearby organs. External radiotherapy directs beams from a machine outside the body; internal radiotherapy places a radioactive source in or near the area being treated. The team may use scans and marks on the skin to reproduce the same position each visit. Radiation can affect healthy cells in the treatment field, which helps explain effects such as tiredness, skin changes or irritation in the treated area. The exact effects depend on the body region and the dose plan. Radiotherapy may be used alone, before surgery to shrink a tumour, after surgery to reduce the chance of remaining cancer cells, or alongside other treatment.

Keep the treatment appointments arranged by your oncology team and follow their instructions about skin care, food, medicines and activity. Tell them about implanted devices, pregnancy or a possibility of pregnancy, and any symptoms that began before treatment. Wear comfortable clothing that leaves the treatment area accessible. Do not apply creams, deodorant or other products to the treatment field unless your team recommends them. Ask how to manage tiredness and whether you need help with travel or daily tasks.

Contact your radiotherapy team promptly if treated skin becomes increasingly painful, blistered or broken, or if you cannot keep fluids down. Seek urgent medical help for severe breathlessness, sudden confusion, heavy bleeding or a rapidly worsening condition. New symptoms during treatment can have several causes, so describe when they started and which area was treated.

Ask which type of radiotherapy is planned, what area will be treated, how many visits are expected, and which side effects are most relevant to that body region. You can also ask how treatment will fit with surgery or medicines, what activities are suitable, and whom to contact between appointments.