Primary Evidence-Based Study On The Diagnosis Of Lung Cancer

Since 1990s, the clinical research of lung cancer has obtained a rapid developingchance with the development of evidence-based medicine (EBM), especiallyevidence-based oncology. In 1996, Sackett named EBM as: "the conscientious,explicit, and judicious use of the current best evidence in making decisions about thecare of individual patients". Different from the traditional clinical medicine, EBM is akind of rational medicine non experimental medicine. It is established on the basis ofmodern clinical epidemiology. EBM can make patients get better care by seeking andusing scientific evidence in clinical practice.Recently, the emphasis on the strategy about diagnosis and treatment of lungcancer has been transmitted to screening for early lung cancer according to clinicalsymptoms of lung cancer since the appearance of a large amount of research results ofRCT and clinical guidelines based on the primary principles of EBM.At present, the major diagnostic methods of lung cancer refer to Cytology, Imageand Histology, etc. The diagnostic tests which are beneficial to the diagnosis of lungcancer include X-ray, ECT, CT, PET and serum tumor markers, etc. Considering eachkind of tests has its prons and cons, people have divided all the diagnostic tests intofront-line and second-line tests according to the need of clinical practice. Thefront-line tests include chest PA & LAT, sputum cytology and B-ultrasound. They are the most basic diagnostic tests of lung cancer because they are adaptable to both firstvisit patients and screening for the high risk crowd. In addition, low-dose spiral CTand fibrobronchoscope can be added into front-line tests under some condition.Second-line tests refer to selecting some proper tests according to different clinicalcondition of each patient based on the results of front-line tests. Their action aims atmaking clear lesion's characteristics or whether or not the occurrence of distantdiffusion, and deciding the treatment strategy. Second-line tests mainly include chestor brain MRI, PET, Thoracocentesis, needle biopsy in cervical lymph node,mediastinoscopy, SPECT and serum tumor markers, etc.The author had designed "diagnostic items collecting table of lung cancer cases"on the basis of systematic literature review and experts consulting by surveyingroutine clinical diagnostic tests of lung cancer and chief complaints of first visitpatients, and set up "data input system" by using data management software ofEpidata 3.1. Furthermore, Diagnostic Database of of Lung Cancer Cases had beenestablished by inputting the related information of 1100 primary lung cancer casesand 1000 benign pulmonary lesion cases as controlled. In the end, diagnostic instanceof lung cancer cases had been retrospectively analyzed and studied from followingthree aspects by using SPSS 13.00 software:1. Referring to "Clinical Guideline of Lung Cancer Diagnosis and Staging"published on "Chinese Journal of Lung Cancer" issue 5, 2003, we had evaluatedclinical application of routine diagnostic tests of 611 lung cancer cases by usingMcNemarx~2 test. The results showed as follows:1.1 Cough was the most routine clinical symptom of lung cancer patients. Atthe same time, symptoms of cough, blood sputum, chest pain and shout breath lastedabove two weeks in terms of 93.8%(375/400), 86.1%(130/151), 85.5%(142/166) and 87.1%(88/101) lung cancer patients respectively.1.2 There were more male patients in squamous carcinoma while more femalepatients in adenocarcinoma; pathological types of middle-age and elderly patientsabove 40 were mainly composed by squamous carcinoma and adenocarcinoma; about9.5% lung cancer patients had no symptoms during diagnostic period.1.3 Positive rate of sputum cytology is 41.3%, serum CEA 48.9%; detectingrate of X-ray plus CT plus CEA group is only 13.4% while X-ray plus CT plussputum cytology group 14.7%. Therefore, advanced survey would be done todemonstrate whether factors such as the course of disease, doctor's experience andover depending on high techniques influence the selection of diagnostic tests or not.1.4 81.8%(500/611) of lung cancer patients had carried through X-rayinspection, among of them, 456 cases took chest PA & LAT, thus, positive rate hadbeen improved to 73.5% from 71.4%; although CT inspecting rate was 45.8%,positive rate of its reached to 97.9%. In addition, only 36.7%(123/335) X-raysuspected cases had carried through CT, but positive rate got to 97.6%(120/123),hinting that CT inspection should be selected in clinical practice in terms of X-raysuspected cases.1.5 Since PET inspection had been selected by 71 NSCLC patients among ofthem 50 beingⅢA-Ⅳ, in accordance with the suggestion of the guideline mentionedabove, it could be concluded that PET had been applied rationally in routine clinicalpractice.1.6 Inspecting rate of fibrobronchoscopy was 44.2%, positive rate 93%, ifdeveloping parallel test with X-ray and CT, then, positive rate 100%. Additionally,only 89Ⅰ-ⅢA patients had carried through fibrobronchoscopy, and it was differentfrom the suggestion mentioned above, therefore, it was demonstrated thatfibrobronchoscope should be used byⅠ-ⅢA patients in order to reduce omission diagnostic rate and mistake diagnostic rate.1.7 Although only 15.4% cases had carried through CT locating percutaneousneedle biopsy, its positive rate got to 96.8%, while inspecting rate of bronchoscopicneedle biopsy was 20.6%, positive rate 88.9%. The evaluation results of consistencyof these two tests showed that both of them had consistency of positive rate whenused in lung cancer patients. Advanced study was still needed in order to demonstratewhether there was overdiagnostic problem in clinical practice or not.2. According to principles of EBM used in diagnostic tests, clinical informationof 140 lung cancer cases and 95 benign pulmonary lesion cases had beenretrospectively analyzed, and the accuracy and strength supplement of X-ray, CT andfibrobronchoscope in the diagnosis of lung cancer had been studied. The resultsshowed as follows:2.1 The accurate rate of X-ray to central lung cancer was 62.5%, peripherallung cancer 78%, and thin bronchuses lung bubble cancer 66.7%, that was, over 60%lung cancer patients could be clinically diagnosed only by X-ray. In addition,although pre-test probability of a suspected case was only 30%, when X-ray resultwas(+), his post-test probability reached to 71.67%, thus, it could be concluded thatX-ray was surely the first selected test in the diagnosis of lung cancer.2.2 Since the sensitivity and positive predictive value of CT reached to 92.1%and 90.8% respectively, even if the pre-test probability of a suspected case was 30%before taking X-ray, when X-ray result was(+), the post-test probability was 71.67%,if developed serial test with CT, the post-test probability reached to 94.44%. Thediagnostic accuracy of lung cancer had been greatly improved. Additionally, theaccurate rate of central lung cancer was higher than that of peripheral lung cancer byCT scans, that is, omission diagnostic rate of CT to central lung cancer was increased.2.3 The accurate rate of central lung cancer was 95.8% by fibrobronchoscopy. Among the three diagnostic tests, the sensitivity, specificity, positive predictive valueand positive likelihood ratio of fibrobronchoscopy were the most highest. It could beconcluded that fibrobronchoscopy had a higher value in the diagnosis of lung cancercompared with X-ray and CT. If fibrobronchoscopy developing serial test with X-ray,its positive likelihood ratio would reach to 173.5, led to post-test probabilityincreased to 98.67% from 71.67% under the condition of pre-test probability being30%. This result would be important to the instructing utility of diagnostic principleof EBM being from simple to complicated, from unwound to wound in clinicalpractice.3. According to the subjective and objective diagnostic evidences of lung cancer,single variable Mantel-Haenszel analysis of major diagnostic influencing factors wasimplemented. The results showed that: blood sputum, chest pain, shout breath, thin,feeling tired, anorexia, local diffusion and distant metastasis had a higher OR valuerespectively, P value was＜0.05. There was a significant difference between casegroup and controlled group. In addition, smoking, environment pollution, occupation,nutrition and diet, chronic pulmonary disease, family history of tumor, genetic riskwere the main risk factors of lung cancer, plus the clinical valued diagnostic tests oflung cancer including all the imaging techniques and serum tumor markers, thus,resident, smoking history, sputum cytology, X-ray, CT, serum CEA,fibrobronchoscope and its direct signs, bronchoscopic needle biopsy and CT locatingpercutaneous needle biopsy could be designated as the valued indexes of diagnosticmodel of lung cancer. Furthermore, individual diagnostic system of lung cancer hadbeen developed according to Microsoft VB6.0 and C language in order to predictpost-test probability of patients under different pre-test probability. After theprospective observation of diagnostic model and automatic diagnostic system of lungcancer by using 113 cases, it could be obtained that both of them had a higher accurate rate to lung cancer patients and were significant to the diagnosticstandardization of lung cancer and to the decrease of omission diagnostic rate inclinical practice.All in all, this paper had firstly evaluated clinical application of routinediagnostic tests of 611 lung cancer cases by referring to "Clinical Guideline of LungCancer Diagnosis and Staging". Secondly, the accuracy and strength supplement ofX-ray, CT and fibrobronchoscope in the diagnosis of lung cancer had been studiedaccording to principles of EBM used in diagnostic tests. Thirdly, single variableMantel-Haenszel analysis of major diagnostic influencing factors was implementedaccording to the subjective and objective diagnostic evidences of lung cancer; anddiagnostic model and individual diagnostic system of lung cancer had been designedand developed respectively. In the end, the aim of screening and optimizingdiagnostic strategy had been primarily reached on the basis of individualcharacteristic of patients.