Surgical implications of the new IASLC/ATS/ERS adenocarcinoma classification

Abstract

A new adenocarcinoma classification was recently introduced by a joint working group of the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS) and European Respiratory Society (ERS). A distinction is made between pre-invasive lesions, and minimally invasive and invasive adenocarcinoma. The confusing term ''bronchioloalveolar carcinoma'' is not used any more and new subcategories include adenocarcinoma in situ and minimally invasive adenocarcinoma.Due to a renewed interest in screen-detected nodules and early-stage lung cancers of ,2 cm, this classification also has profound implications for thoracic surgeons.In this article, surgical topics are discussed: the role of a minimally invasive approach, especially video-assisted thoracic surgery, limited resection for early-stage lung cancer, the extent of lymph node dissection, the accuracy of intraoperative frozen section analysis, management of multiple lung nodules and prognostic factors in operated patients. Specific key issues are presented based on the current evidence and areas of surgical uncertainty are defined providing a basis for further studies.Thoracic surgeons will play a major role in the application and global introduction of this new adenocarcinoma classification. The remaining controversies regarding the precise diagnosis and management of early-stage lesions will have to be resolved by multidisciplinary and international collaboration.

The Demise of the Term Bronchioloalveolar Carcinoma

“…Adenocarcinoma in situ and minimally invasive adenocarcinomas are of special interest because of their 100% and near 100% 5-year survival, respectively, if completely resected. 30 As Borczuk notes, some criteria are more straightforward than others: ''Some criteria are straightforward, such as invasion of the pleura, vessels or airway walls. Once there is confluent scar or desmoplasia in association with glands, this represents invasive adenocarcinoma.…”

“…Notably, the micropapillary pattern, associated with a poor prognosis and a higher rate of node metastasis, is characterized by malignant cells growing in micropapillary tufts lacking fibrovascular cores. 30 The cells can be detached, connected to alveolar walls, or both, and floating ringlike glandular structures can be seen within the alveolar spaces. The lepidic pattern of growth, with tumor cells growing along preexisting alveolar structures, is characterized by the absence of acinar, solid, papillary, or micropapillary patterns of tumor cell growth.…”

“…34 A metastatic mucinous adenocarcinoma from a nonpulmonary primary may be seen lining preexisting alveolar walls and must be distinguished from primary pulmonary mucinous adenocarcina. 30 Ultimately, examination of the term bronchioloalveolar carcinoma serves as a historical example of the vibrancy of a utile, descriptive term that over time, with increased medical understanding, ran its course and attained obsolescence. It also serves to highlight the potential risk with the advancement of medical understanding of a term being overused to describe too many similar (but ultimately distinct) lesions, from which a term's demise is ultimately derived.…”

Differentiating Preinvasive from Invasive Lung Adenocarcinoma Appearing as Part-Solid Ground-Glass Nodule Using CT Value and Solid-Part Diameter

“…On the other hand, over a third of part-solid GGNs are preinvasive lesions, i.e. AIS or AAHs, and can be managed with follow-up alone or limited surgical resection (9)(10)(11). Therefore, it is important to accurately differentiate these preinvasive lesions that appear as part-solid GGNs from more advanced ones such as MIA and IAC.…”

Surgery compared to stereotactic body radiation therapy for early-stage non-small cell lung cancer: better, equivalent or worse?

“…Sublobar resection, especially wedge resection, was only accepted for compromised patients with a high cardiopulmonary comorbidity precluding a formal lobectomy. This changed with the new millennium and sublobar resection emerged as a potentially valid oncological treatment for very earlystage NSCLC, especially for pre-invasive or minimally invasive lesions (4). At the same time, similar to stereotactic brain irradiation, newer radiotherapy techniques allowed to precisely deliver a high dose of radiotherapy to smaller, peripherally located lung lesions, so-called stereotactic body radiation therapy or SBRT (5).…”