While there is a lot of variability in the clinical behavior of bronchioloalveolar carcinoma (BAC), there are some commonly observed findings that are now leading lung cancer experts to consider it as a distinct clinical entity worthy of special consideration for management. Among the important areas for potentially special clinical management is in surgical management of early stage disease. As noted in the last post, the most well differentiated BAC lesions have a very low likelihood of demonstrating nodal spread and have a remarkably high survival at 5 years, approaching 100%. However, they can be multifocal through the lungs and are sometimes managed by multiple surgical resections over many years. With that potential to have small, slow-growing lesions emerge over many years and even over decades, but with a very finite amount of lung tissue to work with, BAC lesions have been a leading consideration for smaller, sublobar resections as an alternative to a full lobectomy (see summary of options in post here) that has generally been the default cancer surgery for lung cancer.

Several of the leading thoracic surgeons in the world, particularly those with an interest in BAC and smaller surgeries, converged in NYC in November of 2004 as part of the first "consensus conference" on BAC (I participated on a committee that focused on systemic (whole body)therapy for advanced BAC) to discuss the state of the art and most relevant management questions, from which they produced a report (abstract here). Largely from a collection of Japanese retrospective studies of early stage BAC, a clear picture has emerged. First, lesions that appear on CT as hazy ground-glass opacities (GGOs) appear to represent noninvasive BAC, while the solid component on CT scans is highly likely to represent invasive adenocarcinoma. Second, smaller lesions (2 cm and smaller) that are predominantly GGO on CT, BAC under the microscope have a remarkably good survival and an exceptionally low likelihood of node involvement.

On the basis of this work, a couple of trials are now being conducted to ask whether small lung cancers can be treated as well with sublobar resections as a full lobectomy. One of these is being conducted in Japan, looking specifically at adenocarcinomas less than 2 cm. A US-based trial, CALGB 140503, is now active and randomizing 1300 patients with peripheral lung cancers up to 2.0 cm to receive either a lobectomy or sublobal resection. The CALGB trial is being conducted with the participation of the other cancer cooperative groups throughout the US, meaning that we'll be asking this question for a few years to come. In the meantime, lobectomy remains the standard approach for resectable lung cancer, but if there are a subset of people who may be the best candidates for smaller surgeries, who may have cancers least likely to need extensive resection and perhaps most likely to benefit from the sparing of lung tissue that would be valuable to continue to have later, especially if additional lesions need surgery in the future, as may well occur with BAC.