i WORLD JOURNAL OF SURGICAL ONCOLOGY

Full list of author information is available at the end of the articleBackground Adenocarcinoma is the most common histological type among lung cancers. As with malignancies in other organs such as the breast and cervix, where carcinomas are defined as non-invasive, micro-invasive or invasive, the extent of the invasive component in lung adenocarcin-omas is associated with clinical outcomes [1]. To address advances in oncology, molecular biology, pathology, radi-ology, and surgery, an international multidisciplinary classification was sponsored by the International Associ-ation for the Study of Lung Cancer (IASLC), the American Thoracic Society, and the European Respiratory Society [2]. Adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) with fibrous stromal invasion are newly introduced subtypes, while the older term of bronchioloalveolar carcinoma does no longer exist according to new IASLC classification of lung adenocar-cinoma. AIS is a localized small (≤3 cm) adenocarcinoma, the growth of which is restricted to neoplastic cells along preexisting alveolar structures without stromal, vascular or pleural invasion. Papillary or micropapillary pattern