This month’s Journal of Thoracic Oncology includes a landmark article, written by a multidisciplinary group of lung cancer experts that features several of the leading lung cancer pathologists in the world, that is attempting to do no less than present a new categorization of the pathology of lung cancer, focusing primarily on adenocarcinomas, but also touching on other lung cancer subgroups. Among the concepts included is a proposal that the term bronchioloalveolar carcinoma (BAC) be discontinued and recategorized based on whether patients have any invasive component to their lung cancer or not, and whether is is mucinous or non-mucinous. As significant as it is to redefine an entire disease of BAC, the concepts it introduces have implications that actually lead to a fundamentally different way of thinking about lung cancer, or at least NSCLC.
Only a few years ago, oncologists saw lung cancer as divisible into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), with very little relevance to any division beyond that point. We knew that patients with NSCLC could be categorized into having adenocarcinoma (including the subset of that larger group, bronchioloalveolar carcinoma (BAC), squamous, large cell and large cell neuroendocrine carcinoma, and into those with and without a significant smoking history, and other demographic variables, but they weren’t a primary focus when we didn’t perceive that these differences had clinical significance in our treatment recommendations. And at that time, most people received remarkably similar treatments, with first line trials in advanced NSCLC incredibly commonly designed as carbo/Taxol (paclitaxel) +/- new drug, and second line trials of Taxotere (docetaxel) +/- new drug, or a direct comparison to placebo in previously treated patients.
General Introduction to Small Cell Lung Cancer
Lung cancer consists of two major types: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Approximately 85% percent of all lung cancer patients have NSCLC, and the remaining 15% have SCLC.
In 2010, the American Cancer Society has estimated that approximately 222,000 new cases of lung cancer will be diagnosed, of which 35,000 will have SCLC. Even though both subtypes are lung cancers, they are considered as separate diseases in most ways, and the management of these two cancers is different. It is important to recognize that the treatments applicable for NSCLC, including many newer agents that have been approved and are the subject of increasing research and media attention, are not clearly relevant for patients with SCLC.
I had the opportunity to sit down with Dr. Matthew Horton, a pathologist who works with my own group at Swedish Cancer Institute in Seattle, at a pathology company called CellNetix. He did subspecialty training in lung pathology and is a terrific resource for my colleagues and me, and now for a wider audience.
The first part of our discussion focused on the major subtypes (called histologies) of NSCLC, including adenocarcinomas, squamous cell carcinomas, large cell carcinomas, and the related large cell neuroendocrine carcinomas, along with a significant fraction of NSCLC tumors that can’t be classified despite our efforts. So check out the links below for the audio and video versions of our discussion (the video with a few images of what we’re talking about), and the associated transcript and figures.