Radiation pneumonitis after chest radiotherapy

Radiotherapy aims radiation at a tumour, but lung tissue near the target inevitably receives some dose. Planning techniques try to limit how much healthy lung is exposed, using shaped beams and, for some patients, highly focused treatment. Even so, the cells lining the air sacs and the small blood vessels can become inflamed, which makes breathing less efficient. The amount of lung exposed, the total dose, any previous chest radiotherapy, concurrent chemotherapy or targeted drugs and pre-existing lung disease all influence the risk.

The NHS lists a range of general radiotherapy effects, including tiredness, swallowing problems and skin soreness. Lung inflammation is a different effect that is specific to treatment involving the chest, and it deserves separate attention because it can be mistaken for infection or for the cancer itself.

Cancer Research UK explains that soon after chest radiotherapy a person might have a dry cough or shortness of breath, which it calls acute radiation pneumonitis, and that a cough and breathlessness may start months after treatment in a chronic form. In practice, symptoms most often appear within the first few months after finishing, may be gradual, and often begin as a nagging dry cough, especially at night or on exertion. Some people have chest discomfort, a low-grade fever or fatigue.

Symptoms like these can also be caused by chest infection, a blood clot in the lung, heart strain, fluid around the lung, recurrence of cancer or drug-related lung injury. For that reason, new breathlessness after treatment should be assessed rather than assumed to be pneumonitis.

• A new dry cough that does not settle.

• Breathlessness that is worse than before treatment or is progressing.

• A raised temperature or feeling flu-like.

• Coughing up a lot of mucus, which Cancer Research UK says to report.

Doctors begin with the timing and the radiotherapy plan, then examine the chest and measure oxygen levels. A chest X-ray may be normal early on; a CT scan is more sensitive and often shows changes that follow the shape of the radiation field. Lung function tests, which Cancer Research UK says may be done to check how well your lungs work, show reduced gas transfer. Blood tests and sometimes sputum samples exclude infection, and further imaging may be done to look for blood clots or cancer progression.

Mild cases may need only observation and cough relief. For moderate or severe pneumonitis, Cancer Research UK notes that steroids or other medicines can help people breathe more easily. A course of corticosteroids is usually started at a higher dose and then reduced gradually over several weeks, because stopping too fast can cause symptoms to return. While on steroids, stomach protection, blood sugar checks and attention to infection risk are standard, and the team will explain any precautions.

Oxygen is provided if levels fall, and inhalers may help if airway narrowing contributes. Antibiotics are given only when infection is suspected, since pneumonitis itself is not an infection.

In some people inflammation heals with scarring. Radiation fibrosis develops over months to years and causes a permanent loss of lung volume within the treated area. It may cause no symptoms when the area is small and the rest of the lungs are healthy. When more lung is affected, or the person has COPD, breathlessness on exertion can be lasting.

Pulmonary rehabilitation, which combines exercise training, breathing techniques and education, helps many people with chronic breathlessness. Stopping smoking, vaccination against flu and pneumococcus where advised, and prompt treatment of chest infections protect remaining lung function.

Contact your radiotherapy or oncology team, specialist nurse or out-of-hours oncology line promptly with new breathlessness or cough, because they can arrange assessment quickly. Call 999 for severe breathlessness, blue lips, chest pain or collapse. Keep a note of when symptoms began and any medicines you take, as this helps the team to distinguish pneumonitis from other causes.