BackgroundLung cancer is a leading cause of cancer-related mortality in Sri Lanka and throughout the world. The latest staging system for lung cancer is the tumor node metastasis (TNM) 7th edition in which there are major changes to the previous version. The objective of our study was to find out the implications of TNM7th edition on lung cancer staging in a resource limited setting, and to compare it with the previous TNM 6th edition.MethodsPatients with histologically proven lung cancer consecutively presented to respiratory unit of Teaching Hospital Kandy, Sri Lanka were recruited to the study over a period of one year from April 2010 to March 2011. They were staged using CT, ultrasound scan of abdomen, bronchoscopy and CT spine and brain when necessary. Staging was done using TNM 7 as well as TNM6. Surgical or non-surgical treatment arms were decided on staging and the number of patients in each treatment arm was compared between the two staging systems.ResultsOut of 62 patients, thirty four patients (54%) had metastatic disease and 19 (30%) of them had pleural effusions (M1a), while 15 (24%) had distant metastasis (M1b). When compared to TNM6 there was no difference in the number of patients in T1 category, but the number in T2 was higher in TNM7 (25 Vs 20). Similarly the number in T3 group was higher in TNM7 (11 Vs 5) and the number in M category was doubled (34 Vs 17 [Chi-6.46, p = 0.011]) compared to TNM 6. The number of patients suitable for surgery were 17(27.5%) in TNM 7 and 18(29%) [Chi-0.02, p = 0.88] in TNM6.ConclusionsThis study shows that a significant proportion of patients were having advanced disease with distant metastasis on presentation. The number of patients falling to stage IV is significantly higher when staged with TNM7 but there was no significant difference in the number of patients undergoing surgery when TNM 7 was used compared to TNM6.