Predicting spread through air spaces (STAS) preoperatively: can imaging help?
More than 80% of primary lung cancers are non-small cell lung carcinomas (NSCLCs), with adenocarcinoma the most common histologic subtype of NSCLC. Diagnosis of NSCLC is primarily made by histologic assessment, which also informs treatment selection (1). Lung adenocarcinoma is well-known to be histologically heterogenous, as reflected in the 4th edition of the World Health Organization classification, which recommends the use of histologic subtyping in 5% increments. The five major histologic subtypes are lepidic, acinar, papillary, micropapillary, and solid (1). Predominant subtype is predictive of clinical behavior: lepidic is regarded as low-risk, acinar and papillary as intermediate-risk, and micropapillary and solid as high-risk (2). Ground glass opacity (GGO) on computed tomography (CT) has been shown to be associated with lepidic growth and consolidation is associated with invasive growth.