Can immunosuppressants, such as azathioprine (Imuran) or cyclophosphamide (Cytoxan), cause lung cancer?

From the Guidelines

Immunosuppressants like azathioprine (Imuran) and cyclophosphamide (Cytoxan) are associated with an increased risk of developing certain cancers, including lung cancer, though the absolute risk remains relatively low. These medications work by suppressing the immune system, which can impair the body's natural ability to identify and destroy abnormal cells that could become cancerous. According to the most recent evidence from 1, when considering immunosuppressive medications or biologics for patients in the setting of malignancy, it is recommended to consult with the patient’s oncologist and take into account activity of the disease, patient’s age, characteristics of the previous cancer, and the time since completion of cancer treatment.

Key Considerations

• The risk of developing lung cancer specifically appears to be modestly elevated with long-term use of these medications, particularly in patients who have other risk factors such as smoking 1.
• Cyclophosphamide has been more strongly linked to bladder cancer and blood cancers, while azathioprine has associations with skin cancers and lymphomas.
• The cancer risk generally increases with higher cumulative doses and longer duration of treatment.
• For patients requiring these medications, regular monitoring is essential, including chest imaging when clinically indicated, as suggested by 1.

Recommendations

• Regular monitoring is essential for patients requiring immunosuppressants, including chest imaging when clinically indicated.
• The benefits of these medications in preventing disease progression or organ rejection often outweigh the potential cancer risks for many patients with severe autoimmune conditions or organ transplants.
• A shared therapeutic decision-making approach should be utilized to reach an informed decision, respecting the patient’s preference, especially in patients with a history of malignancy 1.

From the Research

Immunosuppressants and Lung Cancer

• There is no direct evidence in the provided studies that immunosuppressants, such as azathioprine (Imuran) or cyclophosphamide (Cytoxan), cause lung cancer 2, 3, 4, 5, 6.
• The studies focus on the use of immunosuppressive drugs in treating various diseases, including systemic sclerosis-related interstitial lung disease, and their efficacy and safety in these contexts 3, 5, 6.
• The potential side effects of immunosuppressive drugs are discussed, but lung cancer is not mentioned as a possible risk 2, 4.
• The studies suggest that immunosuppressive therapies, including cyclophosphamide and azathioprine, can be effective in treating interstitial lung disease, but they do not address the question of whether these drugs can cause lung cancer 3, 5, 6.

Safety and Efficacy of Immunosuppressants

• The safety and efficacy of immunosuppressive drugs depend on various factors, including the patient's clinical condition, genetic characteristics, and the underlying disease 4.
• The studies emphasize the importance of careful dosing and monitoring of patients taking immunosuppressive drugs to minimize the risk of adverse events 2, 4.
• The use of sequential therapies, such as cyclophosphamide followed by azathioprine, can be effective in treating certain diseases, but the potential risks and benefits must be carefully considered 3, 6.