When chemotherapy and radiotherapy affect the same area

It cannot tell you whether your medicines will cause a reaction in a treated area. That depends on the medicines, the area and how you respond.

It also cannot diagnose a skin or other reaction. Show any new change to your team promptly.

Given together or one after the other

When chemotherapy is given during radiotherapy, known as chemoradiation, effects in the treated area are usually stronger. When it is given before or after, effects can still overlap. Our page on chemoradiation explains what to expect when the two are combined, and our radiotherapy pages cover radiation effects in detail.

How radiation recall looks

Recall on the skin usually looks like sunburn confined to the shape of the previous radiotherapy field, with clear edges. It may itch, burn, swell or peel. In the lungs, it may cause cough or breathlessness. Because the pattern matches old treatment, your team can often recognise it quickly.

When recall can happen

Recall can appear within days of starting a new medicine, or after several treatments. It has been reported even many years after radiotherapy finished. This is why it matters to tell every new oncologist about past radiotherapy, even if it was long ago or for a different cancer.

What causes recall

The exact reason is not fully understood. It is thought that tissue treated with radiation carries lasting changes that make it react more strongly when certain medicines are given later. Not everyone who has these medicines after radiotherapy develops recall; most people do not. Researchers continue to study it.

Deciding whether to continue a medicine

If recall happens, your oncologist decides whether to pause, continue with extra care, or change the medicine. Sometimes the same medicine can be given again once the reaction settles, with or without a lower amount or steroid cover. This is always your oncologist's decision, not something to change yourself.

Skin care during treatment

Wash treated skin gently with lukewarm water and mild soap, pat dry, and use only the moisturisers your team recommends. Avoid perfumed products, hot water bottles, ice packs and tight clothing over the area. Our skin care pages give practical advice for sore or peeling skin during treatment.

Home remedies

Turmeric, oils, aloe products or other home remedies may irritate treated skin or hide an infection. Some can also affect how skin heals. Ask your team before applying anything to a treated area, even products that seem gentle or natural. Bring any product to your appointment so the team can check it.

Lung effects

After chest radiotherapy, some chemotherapy and immunotherapy medicines can add to lung inflammation. A new dry cough, breathlessness or fever needs prompt review, and a chest scan may be needed. Treatment with steroids is often effective when problems are caught early, so do not wait.

Bowel and bladder effects

Pelvic radiotherapy followed by medicines such as capecitabine or irinotecan can make loose motions more likely. Drink plenty of fluids, follow the anti-diarrhoea plan your team gives you, and call if loose motions persist or you feel dizzy. Blood in urine or stools always needs checking.

Blood counts

Radiotherapy to large bone areas, such as the pelvis or spine, reduces the marrow's reserve. Chemotherapy given afterwards may lower counts more than expected. Your team may check blood tests more often or adjust the plan to keep you safe from infection and bleeding.

Treating the same area again

Sometimes cancer returns in or near an area already treated with radiotherapy. Giving further radiotherapy there requires specialist planning because healthy tissue has limited tolerance. Chemotherapy may be used instead or alongside. Your radiation oncologist will explain what is possible and safe. A second opinion can help in complex situations.

Long-term changes

Treated tissue can remain firmer, darker or more fragile for years, and overlap with chemotherapy may add to these changes. Heart and lung effects from chest treatment may need long-term checks. Keep your treatment summary and share it with any doctor you see in the future.

What to do next

Keep a record of every area treated with radiotherapy, tell each oncologist about it, look after treated skin gently, protect it from the sun, and report redness, cough or bowel changes in a treated area straight away.