Imaging in the breathless cancer patient

•. Although the aetiology of breathlessness is complex, the important treatable and lifesaving causes to identify on imaging are a few common pulmonary infections in the immunocompromised host, pulmonary embolism, drug- and radiation-induced lung injury and the direct effects of malignancy. •. Imaging in the breathless cancer patient should be guided by clinical signs and symptoms. Chest radiography is a useful initial imaging investigation, but the abnormalities, if apparent, may be non-specific. •. Cross-sectional imaging interpretation in the immunocompromised breathless cancer patients can pose diagnostic challenges as the imaging features of infection can mimic and overlap with those of drug- and radiation-induced lung injury. •. Malignancy is a pre-thrombotic state; the incidence of pulmonary embolism can be as high as 10% in asymptomatic patients. •. Awareness and recognition of rarer causes of breathlessness such as drug-induced pulmonary haemorrhage, pulmonary extramedullary haemopoiesis and post-pneumonectomy syndrome may prompt early management. Breathlessness or dyspnoea is a common and distressing symptom among cancer patients. The causes can be complex and multifactorial, and arise from anatomical, physiological, psychological and social interactions. Breathlessness may be related to infection (in the immunocompetent or immunocompromised setting), chemotherapy or radiotherapy, be a direct effect of the underlying cancer or be unrelated to the underlying malignancy. Previous comorbidities such as chronic obstructive pulmonary disease, cardiac impairment and neuromuscular disease can all accentuate breathlessness. Treatment, whether curative or palliative, depends on the underlying aetiology, and radiology usually plays an important role in identifying the incriminating factors. Imaging should be tailored, however, to individual patients, and guided by the underlying histology, clinical presentation and treatment intention. It is important to anticipate and recognise the range of imaging presentations and patterns of disease, and this article aims to review the key imaging features.