T he recent article by Varlotto et al 1 raises issues that are prob- lematic in the recent and current bronchioloalveolar (BAC) literature. The third edition of the 1999 World Health Organization (WHO) consensus classification redefined BAC as an in situ tumor with a pure BAC growth pattern and with no evidence of stromal, vascular, or pleural invasion. 2 This revision was based on data indicating that small, noninvasive BACs rarely metastasize and require no treatment beyond resection. Lymph node metastases were not addressed specifically in the description of BAC, but the description suggested that purely in situ BAC would not be capable to invading lymphatics, and those tumors able to do so would not be classified as BAC. This classification was adopted with minimal modification by the WHO Pathology Panel in 2004, again without comment on lymph node metastases. 3 The application of the new histologic criteria for BAC has created difficulties illustrated in the study by Varlotto et al. 1 It is not clear whether BAC was defined for the study according to the 1999 WHO redefinition, which was not mentioned by the authors until the Discussion section. An unknown number of patients enrolled in the study until at least 2000 very well may not have been BAC according to the current definition. The authors referenced their earlier work, 4 which included 2955 patients with of stages I through IIIB BAC between 1992 and 1998. Of the 1348 patients with stages I through IIIB BAC listed for the period between 2000 and 2002, it is not clear how many had BAC according to the 1999 criteria.
Given all of these open and ongoing questions and issues, we do not believe that the authors' conclusion can be supported that patients with 'N2 BAC' may not receive the same benefit from adjuvant radiation or chemotherapy as patients with non-BAC N2. Their study also highlights the need to define precisely the criteria used to classify a tumor as BAC as well as the need for revisiting the WHO classification itself, a process that currently is underway.