Alternative diagnoses to drug-associated ILD in NSCLC include progression of the cancer, infection, radiation-related lung injury, fluid overload, congestive heart failure and pulmonary embolus. Additionally, some lung cancer patients may develop BOOP or other steroid-responsive inflammatory disorders that cannot be clearly related to drug therapy. Other possible causes of dyspnoea that do not give infiltrates include comorbid diseases such as chronic obstructive pulmonary disease (COPD) and aspiration of food and saliva (particularly in patients with vocal cord paralysis or brain metastases).