The prognostic comparison of 6. TNM and 7. TNM staging system in non-small cell lung cancer

Lung cancer is the leading malignancy in the world in terms of mortality and incidence. TNM classification of lung cancer is very important in treatment modalities, assessment, selection of surgical treatment and the prognosis. Over the years, studies have shown differences in lung cancer staging. International Association for the Study of Lung Cancer (IASLC) has carried out a project under the name of "Lung Cancer Staging Project" for the development and re-organization of the international staging system for lung cancer. T and M descriptors arrangements were made while no N descriptor arrangements were made in the TNM staging that is offered by IASLC. In our study, we aimed to investigate whether differences exist in prognosis by staging the patients with a diagnosis of NSCLC between the years of 2000-2011 clinically and pathologically according to 6th TNM staging and to the revision model published in 2009 (7th TNM). Additionally the patients were investigated according to their age, gender, smoking habit, histopathologic diagnosis, treatment modalities (surgery, chemotherapy, radiotherapy, concurrent or sequential chemoradiotherapy, supportive therapy), clinical staging techniques (conventional staging methods (Thorax CT, abdominal ultrasound or abdominal CT, Bone scintigraphy, MR imaging) or PET CT and MR imaging), life expectancy (died what is the moment of diagnosis, or time elapsed before the deadline date). The study is made with the patients whom ages are ranging from 29 to 87, 446 cases (89.2%) are male and 54 are (10.8%) female, and is carried out on a total of 500 cases. Mean age is 61.65±10:28In the evaluation of tumor size as the T descriptor; T1 tumors were divided as T1a (?2 cm) and T1b (>2-? 3 cm), T2 tumors were divided as T2a tumors (>3-?5 cm) and T2b (>5-? 7 cm), T3-T2c (> 7 cm), T3 (other) according to 7th TNM classification. There was no statistically significant difference between T1a and T1b (p= 0.485), T1b and T2a (p= 0.331), T2a and T2b (p= 0.875), T2b and T2c (p= 0.759), T2c and T3 (other) (p= 0.500) were found in terms of survival .According to the 6th TNM system T stage identification except for tumor size is made by dividing T3, T4-same lobe nodule, T4-other reasons, T4-pleural invasion, M1-lobe satellite nodules in the same lung but in different lobes. There was no statistically significant difference between T3 and T4-same lobe nodule (p= 0.683), T4-other reasons and T4-same lobe nodule (p= 0.615), statistically significant difference was found between T4-pleural invasion and T4-other reasons (p= 0.002) were found in terms of survival.According to the 7th TNM system T stage identification except for tumor size is made by dividing T3-other reasons, T3-same lobe nodule, T4-other reasons, T4-different ipsilateral lobe nodule, M1a-pleural invasion. There was no statistically significant difference between T3-same lobe nodule and T3-other reasons (p= 0.903), T4-other reasons and T3-same lobe nodule (p= 0.811), T4-different ipsilateral lobe nodule and T4-other reasons (p= 0.320) were found in terms of survival, statistically significant difference was found between M1a-pleural invasion and T4-other reasons (p= 0.002).In the 6th clinical TNM classification in M staging M0, M1 (nodule in the same lung different lobe), M1 (other) were compared. M1 stage cases due to the nodules those were at the same lung but at different lobes and M0 stage cases and M1 stage cases due to other reasons did not differ statistically in terms of survival among patients (p= 0.06, p = 0.195). To evaluate the changes made in the M staging of the 7th TMN classification cases of T4M0 and any N, M1a (pleural dissemination), M1a (the opposite lung), M1b (distant metastases) were compared. There was a significant difference in cases those were in stages of T4M0, in any N, and in M1a because of pleural dissemination (p= 0.02) whereas no significant difference in survival between subjects those were in stages of M1a because of pleural dissemination and M1a because of nodule in the opposite lung (p= 0.495). M1a and M1b patients did not differ in terms of survival (p= 0.385, p= 0.968).In the 7th TNM classification there was no statistically significant difference between stage 1A and stage 1B (p= 0.408), stage 1B and 2A (p= 0.75), statistically significant difference was found between stage 3B and stage 4 (p= 0.000).As a result in this study evaluated in terms of tumor size was no statistical difference in survival between patients. It is more suitable that subclassify satellite nodule as T3 due to have a longer survival time than T4 group and subclassify pleural invasion as M1a due to have a shorter survival time. In the 7th TNM classification there is no differences in survival time between stage 1, 2 and 3A and only for stage 3B and 4 survival time is shorter and it is statistically significant. It was thought to be due to the low number of stage 1, 2 and 3A .