Background: This study aims to evaluate the relationship between the clinical T (cT)-stage and metastases (M) in patients with nonsmall cell lung cancer (NSCLC), comparing the 6^th revised edition (old) and 7^th revised edition (new) of the TNM staging system and to assess the potential divergent effects of staging on the course of treatment.

Methods: A retrospective analysis of 136 patients (123 males, 13 females; mean age 60.8 years; range 25 to 83 years) who were diagnosed with NSCLC between January 2007 and January 2009 were conducted. Several variables including age, gender, smoking status previous radiological and/or bronchoscopic findings, and diagnostic and screening techniques which were used to diagnose metastases were determined. Clinical staging (cTNM) was assessed using the 6^th and 7^th revised editions of the TNM staging system.

Results: A total of 41 patients (30.1%) had squamous cell carcinoma, 29 (21.3%) had adenocarcinoma and 66 (48.5%) had histologically not otherwise specified NSCLC. Staging was changed for 23 of the patients, while lower stage of disease, compared to baseline, was found in 15 patients, based on the 7^th edition of TNM the staging system. The most significant changes were observed in stages 3A and 3B, whereas no difference was seen in stage 1 disease. According to the 6^th edition of TNM staging system in terms of M distribution, 72 (%52.9) had no metastases, whereas 64 (%47.1) had metastatic disease. According to the 7^th edition in terms of M distribution, one more patient was diagnosed with non-metastatic disease, increasing the number of the patient in this group up to 73 (53.6%). Of 63 patients with metastases, 17 (%12.5) had intrapulmonary metastases (M1a), while 46 (%33.9) had distant metastases (M1b). No significant difference was seen between the groups in terms of N distribution. Different treatment modalities were followed in 11 of 136 patients (8.1%).

Conclusion: Our study results showed comparable results in both groups, including 6th edition and 7^th edition of the TNM staging system, suggesting a concordance rate of 96.9% (r=0.968; p<0.0001). A poor correlation between T-stage and M score was obtained when the 6^th edition of TNM staging system is used (r=0.170; p=0.048), whereas a stronger correlation between T-stage and M score was observed, using the 7^th revised edition of the TNM staging system (r=0.190; p=0.027).

Keywords : Metastasis; non-small cell lung cancer/classification; stage; tumor size