Comparison Of Clinical And Surgical-pathologic TNM Staging In 180 Patients With Lung Cancer

ObjectiveAccurate clinical TNM staging of lung cancer is essential to choose the optimal therapeutic strategy for lung cancer, determine the severity and assess the prognosis. The inaccurate preoperative TNM staging may make the treatment failure. Clinical over-staging may deny a beneficial surgery for a patient who can benefit from surgery, whereas under-staging may oblige a patient to accept a fruitless or even harmful surgery. The goal of this study is to investigate the coincidence between clinical (cTNM) and surgical-pathologic stagings (pTNM) in 180 patients with lung cancer in order to evaluate the accuracy of our clinical staging and analysis the factors resulted in the disparity, and Guide the multidisciplinary treatment of lung cancer.Materials and methodsFrom January 2008 to February 2009, we carried out a retrospective study of 180 lung cancer cases treated by surgery in thoracic department of China-Japan Union Hospital of Jilin University. Before surgery all cases underwent routine chest X-ray and spiral CT scan of the chest and upper abdomen, brain CT or MRI, bronchoscopy, abdominal ultrasonography, ECT and so on. All cases shuold recieved thoracotomy in two weeks. The major method for local tumour resection was lobectomy, and the method of mediastinal lymph node dissection was systematic mediastinal lymphadenectomy. The shortest diameter of mediastinal lymph nodes >10.0mm under mediastinal window of CT as the clinical diagnostic criteria to define metastasis, and the N classification was made according to the 1997 Mountain International standards. Clinical staging was made acording to the seventh edition of the TNM classification established in 2009. For clinical staging, information is provided by noninvasive or minimal invasive preoperative examination procedures, and for pathologic staging, information is mainly obtained from the findings in invasive surgical procedure and the pathologic evaluations of the excised tissue. Concordance was measured by calculating agreement rates and the kappa value.. When the kappa value is greater than 0.75, means perfect coincidence, when 0.75>Kappa>0.4 means moderate coincidence, and when the Kappa value is less than 0.4, means poor coincidence. Statistical software of PASW18.0 was performed to statistical analysis, the coincident rate between every two T,Nsubstagings were analyzed by the X2 test, when P<0.05 we considered the coincident rates were significant deviation.ResultsThe coincident rate of T staging was 80.6%, and the agreement was moderate (Kappa= 0.688), But in substagings, the coincident rates of T3,T4 is less than 65%, lower than T1,T2 respectively, the results had significant deviation(P<0.05). The coincident rate of N staging was 57.4%, and the agreement was poor (Kappa=0.278), Lymph nodes could be devided into three categories according to the shortest transverse diamate:10~15mm,16~20mm,>20mm, with the increase of the least transverse diamater, we found that sensitivity and negative predictive value were significantly reduced, but the specificity and the positive predictive value were significantly increased. Though the specificity, accuracy, positive predictive value, negative predictive value between the categories of the 16~20mm and the >20mm have not statistical differences, but all with significant statistical difference when they compared with group of 10~15mm. The coincident rate of M staging was 98.9%, Comparised cTNM and pTNM staging, the overall coincident rate of TNM is 70.0% and the coincidence rate is greater than 0.4(Kappa=0.619), Among 54 patients whoes cTNM are changed according to pTNM, 21 (11.7%) cases were overvalued and 33(18.3%) cases were under-valued, in additional, 64.8%(35/54) of patients whoes cTNM are changed resulted from the N staging changed. The substagings of I , II is usually undervalued, then the substaging of III is uaually overvalued. Pre-operative evaluation underestimated far more commonly than it overestimated.Conclusionsl.The methods based on spiral CT to determined cTNM staging can not accurately ditinguish tumours from soft tissue around, especially the anatomical relationship between the lung tumour with the mediastinal tissues,blood vessels and chest wall.2. The poor conformity of N staging is the main reason for leadind to the poor coincidence between clinical TNM and surgical-pathologic TNM staging. The diagnostic criteria of the shortest transverse diamater > 10mm to determine whether the mediastinal lymph nodes were metastasis or not by spiral CT is better than other parameters.3. The methods based on spiral CT play an important role in determining the cTNM precisely, but the present clinical TNM staging of lung cancer is valuable but not very accurate.Other methods such as PET-CT andmediastinoscopy and sone new mimimal invasive surgery techniques should be combined for elevating the accuracy of cTNM staging, especially for N staging.