Lung cancer associated with cystic airspaces (LCCA): A comprehensive literature review undertaken as part of the British thoracic oncology group (BTOG) work programme

Lung cancer associated with cystic airspaces (LCCA) is an increasingly recognised yet under-characterised presentation of non-small cell lung cancer, accounting for approximately 1-4% of cases. Despite growing awareness driven by thin-section computed tomography and lung cancer screening, LCCA remains absent from major international guidelines and classifications, including those of the National Institute for Health and Care Excellence, the International Association for the Study of Lung Cancer, and the World Health Organization. This narrative review synthesises the available evidence to define LCCA as a distinct clinico-radiological entity and to inform future guideline development. LCCA presents heterogeneously, with thin- or thick walled cysts, unilocular or multiloculated morphology, and variable solid components, frequently mimicking benign cysts, bullae, or emphysema. Such ambiguity contributes to diagnostic delay; in the NELSON screening trial, LCCA accounted for 22.7% of missed or delayed diagnoses. Several radiological classifications, notably that of Mascalchi, aid description and risk stratification. Conventional staging is problematic, as measurement of the solid component alone may underestimate true tumour extent, while fluorodeoxyglucose positron emission tomography carries a high false-negative rate. Tissue sampling is similarly complicated by low diagnostic yield and false negative results, underscoring the importance of multidisciplinary team discussion. The natural history follows a stepwise progression from thin-walled cyst to wall thickening, mural nodularity, and invasive disease, with prognosis determined principally by stage, although mural nodularity and increasing solid components confer higher recurrence risk. Treatment broadly mirrors that of solid lung tumours; current guidance advocates targeting the whole cystic lesion for radical therapy rather than the solid component alone, with systemic anticancer therapy appropriate in advanced or multifocal disease. Much current practice is extrapolated from part-solid tumours; consensus on Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation terminology, classification, and staging, supported by prospective registry data, is required to optimise outcomes.