Learning Objectives Understand that lung adenocarcinoma development generally follows step wise progression from pre invasive lesions to invasive disease and is referred to as the adenocarcinoma spectrum. Review key imaging findings including the characteristic radiological appearances of lesions at different phases of lung adenocarcinoma development.

BackgroundLung cancer is the fifth most commonly diagnosed cancer within Australia although is the most common cause of cancer death. [1]While rates of tobacco smoking have declined in Indigenous and non-Indigenous Australians living in non-remote areas, smoking rates amongst First Nations people remain disproportionately high. [2] Although smoking remains a dominant risk factor for the development of lung cancer, additional factors including air pollution, other environmental exposures, genetic susceptibility and the development of certain mutations, particularly in women, appear to play a role. [3-5]Adenocarcinoma of...

FindingsTerminology:Based on Fleischner Society: Glossary of Terms for Thoracic Imaging [10]Ground glass: Area of increased attenuation that does not completely obscure the underlying bronchial and vascular structures. Thin section CT images acquired at full inspiration is required for accurate detection. See Table 1.Nodule: Circumscribed rounded opacity ≤ 30 mm in average diameter. Based on attenuation, nodules can be separated into: ground glass nodules (GGN) – pure ground glass attenuation; also referred to as pure GGN; solid nodules – pure soft tissue attenuation; or part solid...

ConclusionAdenocarcinoma of the lung is the most common histological and screen detected subtype of lung cancer. It is vital that the general radiologist be familiar with adenocarcinoma of the lung when reporting nodules found incidentally or as part of lung cancer screening. An understanding of the stepwise progression of the disease both histologically and radiologically, acknowledging that there is some overlap and heterogeneity with imaging features, is valuable.

References Australian Institute of Health and Welfare. Cancer data in Australia [Internet]. Canberra: Australian Government; [updated Aug 2023; cited 2024 April 3]. Available from https://www.aihw.gov.au/reports/cancer/cancer-data-in-australia/contents/overview-of-cancer-in-australia-2023 Australian Institute of Health and Welfare. Alcohol, tobacco & other drugs in Australia [Internet]. Canberra: Australian Government; [updated July 2024; cited 2024 August 3]. Available from https://www.aihw.gov.au/reports/alcohol/alcohol-tobacco-other-drugs-australia/contents/priority-populations/aboriginal-and-torres-strait-islander-people Lortet-Tieulent J, Soerjomataram I, Ferlay J, Rutherford M, Weiderpass E, Bray F. International trends in lung cancer incidence by histological subtype: Adenocarcinoma stabilizing in men but still increasing in women. Lung Cancer 2014;84:13-22...