Pulmonary adenocarcinoma T1N0M0 and its classification

Over the last decade, use of the term bronchioloalveolar carcinoma (BAC) has come under constant scrutiny as some consider it an anachronism or a term that provides incorrect information about this neoplasm. To that extent, it has recently been suggested to replace the term BAC with that of in situ adenocarcinoma (AIS) or minimally invasive adenocarcinoma (MIA) for small solitary adenocarcinomas with either pure bronchioloalveolar growth (AIS) or predominant bronchioloalveolar growth and ≤5-mm invasion (MIA). However, as of today, there is no comprehensive study of these tumors, and most of what has been published in this context is based on a review of the literature that focused on scattered short series of cases describing either small adenocarcinomas or BAC. More recently, a large series of cases of a more comprehensive nature that included all early-stage adenocarcinomas (T1N0M0) has cast some doubt regarding the need for the proposed change in nomenclature. At the same time, it was suggested that if indeed that notion is maintained, a more serious and comprehensive study of actual cases must be undertaken. The details of the issues surrounding this subject are presented in this review.