distant metastases or other functional/clinical conditions that excluded surgery were also assessed. Tumor histology was coded according to the WHO Histological Typing of Lung and Pleural Tumors (1999); clinical and/or post-surgical staging was performed according to the International System for Staging Lung Cancer adopted by the American Joint Committee on Cancer and the Union Internationale Contre le Cancer [9]. To verify extra-thorax metastases, we reviewed abdominal CT scans and ultrasounds, brain CT scans or MRI, and bone scintigraphy scans. To standardize diagnostic criteria across hospitals we reviewed clinical documentation and when necessary made changes to the original diagnosis/staging; in these instances the reason and the specific changes made were documented in a decision log. Diagnoses from approximately 10% of cases were reviewed and confirmed by an experienced independent pulmonary pathologist from the National Cancer Institute, NIH (Dr. Ilona Linnoila).
