Lung Damage After Cancer Treatment

Cancer treatment can injure the lungs. Some of that injury shows up during treatment. Some shows up months or even years later. The National Cancer Institute puts it plainly: chemotherapy and radiation therapy to the chest may damage the lungs, but you might not notice problems until years after treatment.

This page explains what causes that damage, how it feels, when it is an emergency, and which tests answer the question.

Some lung injuries move fast. Call 911 or go to an emergency department if you have:

• Breathlessness while sitting still, or trouble finishing a sentence
• Sudden shortness of breath, or breathlessness that is clearly worsening hour by hour
• Chest pain that is worse when you take a deep breath
• Coughing up blood, or pink frothy sputum
• Blue or grey lips, fingertips or face, or feeling faint

Call your oncology team the same day, and go to the emergency department if you cannot reach them, for:

• New shortness of breath that has crept up over days
• A new cough with a fever, if you are not currently having chemotherapy
• A dry cough that is new since chest radiation or immunotherapy started

If you are having chemotherapy, a fever of 100.4°F (38°C) or higher is more than a same-day call. The CDC says to call your doctor at once at that temperature. It treats fever during chemotherapy as a medical emergency. Infection can overwhelm a body with low white cells within hours. If you go to an emergency room, say at once that you are on chemotherapy and have a fever.

MedlinePlus gives the same instruction to anyone receiving bleomycin. Call the doctor right away for difficulty breathing, shortness of breath, wheezing, fever, or chills. That is a sound rule after chest radiation too.

Do not start steroids, antibiotics, or extra oxygen on your own. These help some lung injuries and are wrong for others. The team needs to know which problem it is first.

Radiation to the chest. The lungs sit inside the treated area for lung cancer, esophageal cancer, breast cancer, Hodgkin lymphoma, and some sarcomas. The National Cancer Institute lists cough and shortness of breath among the side effects of chest radiation.

Certain chemotherapy drugs. The American Cancer Society names bleomycin and busulfan as drugs that can damage the lungs. Bleomycin is used for Hodgkin lymphoma and testicular cancer. Busulfan is used before some stem cell transplants. MedlinePlus warns that bleomycin can cause severe or life-threatening lung problems, and that the risk is higher in older patients and at higher doses.

Immunotherapy. Immune checkpoint inhibitors can cause pneumonitis, which means inflammation of the lung tissue itself.

Stem cell transplant. Radiation, chemotherapy, and graft-versus-host disease can all inflame the lung after a transplant.

Both chemotherapy and radiation. The risk of lung damage is higher in people who received chemotherapy and chest radiation, rather than one alone.

Radiation pneumonitis is inflammation of the lung caused by radiation. The American Cancer Society reports that it may happen about 3 to 6 months after radiation to the chest.

The signs it describes are:

• Shortness of breath that usually gets worse with exercise
• Chest pain, often worse on a deep breath
• Cough
• Pink-tinged sputum
• Low-grade fever
• Weakness

Some people have no symptoms at all, and it is found on a scan done for another reason.

The American Cancer Society says symptoms often clear up on their own. Some people need treatment to bring the inflammation down. Steroids such as prednisone are what is usually used. With treatment, most people recover without long-term effects. Left untreated or unresolved, it can move on to scarring.

Pulmonary fibrosis means the lung tissue has become stiff and scarred. Once it scars, the lung can no longer inflate fully and take in air.

MedlinePlus lists the usual symptoms of pulmonary fibrosis:

• Shortness of breath
• A dry, hacking cough that does not get better
• Fatigue
• Weight loss for no known reason
• Aching muscles and joints
• Clubbing, which is widening and rounding of the fingertips or toes

There is no cure for fibrosis. Treatment aims at symptoms and quality of life: medicines, oxygen therapy, pulmonary rehabilitation, and in some cases lung transplant. This is why early reporting matters. Inflammation can often be treated. Scar tissue cannot be undone.

Bronchiolitis obliterans is a rarer form of scarring that narrows the smallest airways. After radiation therapy for breast cancer, it is reported in 0.8% to 2.9% of women, and it is usually managed with steroids.

Checkpoint inhibitor pneumonitis can be severe, and in some cases fatal. Its timing is the hard part. In one study cited by the National Cancer Institute, the median time from starting the drug to the onset of pneumonitis was 2.8 months. The range ran from 9 days to 19 months.

That means there is no safe window. Breathlessness three weeks in and breathlessness a year in both need reporting.

For moderate or worse pneumonitis, the usual approach is to hold the drug, give corticosteroids, and follow the person closely.

Pneumonitis is most common in the first 100 days after a transplant. But some lung problems appear much later, even 2 or more years afterwards. Radiation, graft-versus-host disease, and chemotherapy can all be the cause.

Report any shortness of breath or change in your breathing to the transplant team right away. For people with chronic graft-versus-host disease, some doctors run breathing tests every few months.

It is tempting to assume the lung is the problem. Often it is not the only one. In advanced cancer, a median of five different abnormalities contributed to a person's shortness of breath in one study reported by the National Cancer Institute. Correctable causes included bronchospasm in 52%, low oxygen in 40%, and anemia in 20%.

That matters for your appointment. Ask the team to check the treatable things as well as the scarring: anemia, fluid around the lung, blood clots, infection, and tight airways.

• Pulmonary function tests (breathing tests). Spirometry measures how much air you can move and how fast. It shows whether the lungs are stiff, whether the airways are narrow, or both.
• Chest imaging. A chest X-ray or CT scan shows inflammation, scarring, fluid, and infection.
• Arterial blood gas. This measures oxygen and carbon dioxide in the blood.
• Bronchoscopy. A thin tube looks inside the airways and can sample fluid, mainly to rule out infection.
• Biopsy. Rarely needed, but used when the pattern is unclear.

A test done before treatment is worth asking about. A baseline breathing test makes any later change much easier to read.

• Ask which of your treatments carry lung risk, and at what dose you received them.
• Ask whether a baseline breathing test was done, and whether one should be repeated.
• If you had bleomycin, tell every future doctor, surgeon, and anesthesiologist. It stays on your record for life.
• Do not smoke, and ask for help to stop. Smoking adds injury to a lung that has already been treated.
• Ask about vaccination against flu, COVID-19, and pneumococcal infection.
• If breathing changes persist, ask for a referral to a pulmonologist, a lung specialist.
• Ask about pulmonary rehabilitation. It is a supervised exercise and education program that improves function in chronic lung disease.

• Late Effects of Cancer Treatment — National Cancer Institute
• Radiation Therapy Side Effects — National Cancer Institute
• Cardiopulmonary Syndromes (PDQ) Health Professional Version — National Cancer Institute
• Bleomycin Injection — MedlinePlus, National Library of Medicine
• Pulmonary Fibrosis — MedlinePlus, National Library of Medicine
• Radiation Therapy Effects on Different Parts of the Body — American Cancer Society
• Long-term and Late Effects of Cancer — American Cancer Society
• Stem Cell Transplant Side Effects — American Cancer Society