| Part I 18F-FDG Uptake for Prediction EGFR Mutation Status in Non-Small Cell Lung CancerBackground and Objection:Lung cancer is one of the main contributors to cancer-related deaths worldwide. The treatment of non-small cell lung cancer (NSCLC) has seen great advances in the last decade. The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) has a good effect as a treatment for NSCLC cases with activating EGFR mutations. Compared with standard chemotherapy, upfront TKI has a better progression free survival in patients with EGFR mutations. However, a lack of sufficient tumor tissue has an impact on genetic testing in clinical practice.Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT), which is connected to high glucose metabolism, plays an important role in initial staging, restaging after therapy, and radiation therapy planning. Moreover, in the clinical practice, early decreases in FDG uptake are predictive of efficacy of TKI. Therefore, as a noninvasive method, quantification of glucose metabolism with FDG-PET is one way to predict EGFR mutations.We carried out a retrospective study in patients who underwent EGFR mutation testing and pretreatment with FDG-PET/CT in NSCLC, and we discuss the relationships between 18F-FDG uptake, clinical features and EGFR mutation status. We then establish a predictive model for EGFR mutation status, and we validate the model by using prospective samples.Methods and materialsPatientsWe retrospectively investigated the medical records of patients treated between January 2010 and December 2013. All of them met the following entry criteria: diagnosis was made either histologically or cytologically, and the patients underwent EGFR gene testing; PET/CT was performed in previous to any therapy; histopathology was reviewed at Nan Fang Hospital in Guangzhou.Eighty-five patients from January through June 2014 were enrolled and were used to prospectively validate the prediction model. The parameters were collected as before. The EGFR mutation analysis was performed blinded to predicted outcome data. The study was conducted with the approval of the Nan Fang Hospital Institutional Review Board.EGFR mutation analysisEGFR mutations in exons 18,19,20 and 21 were detected by direct sequencing in the pathology department of Nan Fang Hospital in 2010-2012. The Amplification Refractory Mutation System (ARMS) was used to detect exons 18 to 21 in 2013.FDG-PET/CTThe fused PET/CT, PET and CT images were independently assessed by two experienced nuclear medicine physicians. The maximum voxel uptake, reflecting the maximal uptake of FDG within the tumor, was found and its SUVmax was calculated according to the following formula:SUV=tissue radioactivity concentration (becquerels per millilitre)/[injected dose\(becquerels)/patient weight (grams)].The relationships of EGFR mutations with both SUVmax and patient characteristics were evaluated, and a multivariate logistic regression analysis was performed. The model was assessed by area under the receiver operating characteristic curve (AUC) and was prospectively validated during January to June 2014.Results:Three hundred and sixteen patients meeting the criteria were enrolled for model construction. The SUVmax values were significantly lower for EGFR mutations (mean±SD,9.5±5.74) than for EGFR wild-type (mean±SD,12.7±6.43; P< 0.001). The EGFR mutations of non-smokers were more frequent than those of smokers (60.4% versus 20.4%; P<0.001). There were 242 patients (76.6%) with adenocarcinoma. EGFR mutations were more frequent in adenocarcinoma (p<0.001). Most of the patients, whose CT findings revealed a primary tumor size larger than 5 cm, had wild-type EGFR (83.8%; P＜0.001). ROC curve analysis showed that the SUVmax cutoff point was 8.1, for which the AUC was 0.65 (95% CI,0.60-0.72). In addition, multivariate analysis also showed that low SUVmax (≤8.1) was a predictor of EGFR mutations, for which the AUC was 0.77, combining non-smoking history and primary tumor size (≤5 cm). Eighty-five patients were enrolled to validate the predictive model, and the overall accuracy, sensitivity and specificity were 77.6%,64.6% (95% CI 40.7-82.8) and 82.5%(95% CI 70.9-91.0), respectively.ConclusionIn conclusion, the results of the current study, which were validated by a prospective sample, demonstrate that EGFR mutation status is associated with FDG uptake, smoking history and primary tumor size in NSCLC patients. The model can be efficient for determining EGFR mutation status to estimate the combined effects of these three factors, especially when genetic testing is not practical or when there is insufficient tumor tissue. However, for further substantiation of the current results, a large prospective study is warranted.PartⅡFibrinogen for Associating with EGFR Mutation Status and Lymphatic Metastasis in Non-small Cell Lung CancerBackground and Objection:Non-small cell lung cancer (NSCLC) is the most common cancer and the main contributor to cancer-related deaths in China. In the last decade, tyrosine kinase inhibitor (TKI) gefitinib and erlotinib, which specifically target tyrosine kinase (TK) domain of the epidermal growth factor receptor (EGFR), have showed significant effect in NSCLC patients with EGFR mutations. However, sufficient tumor tissue cannot always be obtained for genetic testing in clinical practice. Developing noninvasive techniques to predict the EGFR mutation status could help solve the clinical problem.Fibrinogen, a major acute phase protein synthesized by the liver epithelium, increases in level reacting to blood clotting, infection, wound healing, inflammation and neoplasia. It is increasingly recognized that the level of plasma fibrinogen is associated with human malignancies, such as lung cancer, gastric cancer, esophageal cancer, ovarian cancer and renal cancer. Elevated coagulation may be a key factor of the possibility of metastasis, such as circulating tumor cells. Fibrinogen promotes platelets to adhere to tumor cells, and then aggregates of platelet-fibrin-tumor cells may lead to the potential of metastasis by preventing the natural killer cells from eliminating tumor cells. Previous studies had reported that hyperfibrinogenemia was correlated with lymphatic metastasis in gastric cancer and gallbladder carcinoma, but not in NSCLC. Moreover, no study demonstrates plasma fibrinogen concentration in NSCLC patients as a predictor for EGFR gene mutation status.The aim of current study is to investigate the possible correlation between plasma fibrinogen level and EGFR gene mutation status in NSCLC patients. After that, a predictive model is established for EGFR mutation status.Methods and materialsWe retrospectively investigated the medical records of patients treated from January 2010 to December 2013. All patients were confirmed to have NSCLC and did not receive any treatment. All of them met the following entry criteria:(1) the patients underwent EGFR gene testing after histologic or cytological diagnosis; (2) Plasma fibrinogen was acquired before initiating treatment; (3) PET/CT was performed before any therapy; (4) histopathology was reviewed at Nanfang Hospital, Guangzhou, China. Blood samples from NSCLC patients were obtained within 1 week before any treatment. Fibrinogen was measured by the Clauss method (Sysmex CA-1500, TOA Medical Electronics, Kobe, Japan). Plasma fibrinogen concentration of 1.8-3.5 g/L was recognized as normal. EGFR mutations in exons 18-21 were detected by direct sequencing in the pathology department of Nanfang Hospital in 2010-2012. Plasma fibrinogen was acquired and its association with EGFR mutation status and clinical features was assessed. The Amplification Refractory Mutation System (ARMS) was used to detect exons 18-21 in 2013. A multivariate analysis and a receiver operator characteristic (ROC) curve analysis were performed to identify the potential value of fibrinogen for predicting EGFR mutation status.Results:In total,303 histologically verified NSCLC patients (mean age:60 years±11.6 years,97 females and 206 males) were included. The level of plasma fibrinogen was significantly higher in T2, T3 or T4 stage than in T1 stage (3.55±1.09,3.70±1.29 and 3.90±1.29 vs 3.01±1.19, P＜0.001), and in M1 stage than in M0 stage (3.81±1.33 vs 3.28±1.07, P=0.025). The proportion of patients with high fibrinogen concentration was significantly higher in N2 and N3 stage than in NO and N1 stage (45.2% and 56.5% vs 29.2% and 36.0%, P=0.001). The EGFR mutations of non-smokers were more frequent than those of smokers (60.1% versus 20.6%; P＜0.001). Plasma fibrinogen levels were significantly lower in patients with EGFR mutations than in those with wild-type EGFR gene. (2.95g/L [range,0.84 to 8.61 g/L] v3.57g/L [range,1.38 to 7.44g/L];P＜0.001). In multivariate analysis, logistic regression was utilized and fibrinogen (OR 2.5, CI 1.53-4.51, p＜0.001) and smoking status (OR 5.07, CI 3.01-8.53, p＜0.001), for which the AUC was 0.75, were found to be independent predictive factors.ConclusionIn summary, this study demonstrates, for the first time, that the plasma fibrinogen is an independent predicted factor for EGFR gene mutation status. It is moderately accurate to predict EGFR gene mutation status by combining plasma fibrinogen with smoking history in NSCLC patients. In addition, hyperfibrinogenemia is not only with distant metastasis-associated, but also lymphatic metastasis-associated, suggesting that NSCLC patients with notably elevated fibrinogen level may benefit from aggressive multimodality therapy. However, further independent studies are needed to completely explore the molecular mechanisms between fibrinogen and EGFR gene mutation status, as well as metastasis. |
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