Approximately 80% of all pulmonary malignancies in the United States are non-small cell lung carcinoma (NSCLC) with about 170,000 newly diagnosed cases each year. NSCLC is histologically divided into three tumor types: (i) adenocarcinoma, which accounts for approximately 40% of all NSCLC cases and is the predominant tumor type arising in non-smokers; (ii) squamous cell carcinoma which accounts for 30% of all lung cancers; and (iii) large cell carcinoma.

While classifying a NSCLC into the appropriate histotype can be relatively straight forward in patients whose tumors have been surgically resected (primarily early stage patients), a pathological diagnosis in later stage patients can be much more difficult if the biopsy sample is small and/or disrupted such as those samples obtained by the increasingly common use of core or needle biopsy. Error rates may be as high as 25% when comparing diagnosis on needle biopsy specimens to those obtained on surgical specimens.

Though there is extensive diversity in the molecular physiology of lung tumor histological types and proposed differentially associated markers, there is currently no widely accepted molecular-based tool to help distinguish the different histological types. The histologic classification of non-small cell lung tumors has gained clinical relevance because newly developed targeted therapies show different clinical effectiveness or toxicity dependent upon the histotype of the tumor. Epidermal growth factor receptor (EGFR) inhibitors have been shown to be more effective in certain subgroups of patients including adenocarcinoma patients who were previously treated with chemotherapy and non-smokers. Bevacizumab (Avastin^®), targeted to vascular endothelial growth factor has been shown to improve overall survival in NSCLC patients when combined with a first line of chemotherapy or erlotinib.However, because of adverse hemorrhagic events in patients with squamous cell carcinoma, this drug is recommended by the manufacturer only for use in non-squamous cell patients. Thus, the development of therapies that are more effective or less toxic when targeted to one particular subtype of NSCLC mandates obtaining an accurate subtype diagnosis. Pulmotype is an easy to use, inexpensive assay using traditional IHC technology familiar to the pathologist that can aid the pathologist in diagnosis and, having determined the appropriate histotype, direct the oncologist to the most appropriate course of therapy.