Relationship of T-stage and nodal metastases according to the up-to-date clinical TNM staging in lung cancer

Background: This study aims to evaluate the relationship between the clinical T (cT)-stage and metastases (M) in patients with non-small cell lung cancer (NSCLC), comparing the 6th revised edition (old) and 7th 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 6th and 7th 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 7th 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 6th 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 7th 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 7th 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 6th 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 7th revised edition of the TNM staging system (r=0.190; p=0.027).