目的 探讨血清纤维连接蛋白（fibronectin，FN）在非小细胞肺癌（NSCLC）患者中的表达水平及其临床诊断价值。 方法 本研究首先通过TIMER2.0数据库、GTEx数据库、人类蛋白质图谱HPA数据库分别评估FN在NSCLC中的基因和组织蛋白表达水平。然后选择2021年1月至2023年6月在安徽中医药大学第一附属医院住院的154例高度怀疑肺癌的患者，根据病史与临床表现、影像学检查、病理组织结果等将患者最终分为81例NSCLC患者、73例良性肺部疾病患者。采用免疫比浊法检测血清FN的浓度，采用化学发光法检测CEA、SCC、CYFRA21-1的血清表达水平。 结果 生物信息学分析结果显示FN的基因表达和组织蛋白表达水平均低于正常组织。在血清学分析中，晚期NSCLC患者（Stage Ⅲ—Ⅳ）以及早期NSCLC（Stage Ⅰ—Ⅱ）的血清FN浓度（249.50 ng/mL、305.00 ng/mL）均明显低于肺良性疾病组（429.16 ng/mL）（P < 0.001）。单因素与多因素logistic回归分析结果显示血清FN可明显预测NSCLC的存在。血清FN诊断早期NSCLC的受试者工作特征（ROC）曲线下面积（AUC）为0.790，明显优于CEA（0.618）、SCC（0.653）、CYFRA21-1（0.601）。血清FN鉴别早期NSCLC和良性疾病的最佳临界浓度为347.6 ng/mL，敏感度（71.93%）明显优于CEA（19.30%）、SCC（12.28%）、CYFRA21-1（8.77%）。 结论 血清FN在NSCLC表达水平降低，可能成为一种早期诊断NSCLC的生物标志物。

Objective To investigate the expression levels of serum fibronectin （FN） in patients with non-small cell lung cancer （NSCLC） and evaluate its clinical diagnostic significance. Methods Firstly， the gene and tissue protein expression levels of FN in NSCLC were assessed using the TIMER2.0 database， GTEx database， and Human Protein Atlas （HPA） database. Secondly， from January 2021 to June 2023， a total of 154 patients with lung space-occupying lesions or shadows at the First Affiliated Hospital of Anhui University of Chinese Medicine were enrolled. Based on medical history， clinical manifestations， imaging tests， and pathological histological findings， these patients were categorized into two groups： 81 patients with NSCLC and 73 patients with benign lung diseases. The serum concentration of FN was measured by immunoturbidimetry， while the serum levels of CEA， SCC， and CYFRA21-1 were determined using chemiluminescence. Results The bioinformatics analysis results demonstrated that the gene expression and tissue protein levels of FN were significantly reduced compared to normal tissues. In serological evaluations， serum FN concentrations in patients with advanced NSCLC （Stage Ⅲ-Ⅳ） and early-stage NSCLC （Stage Ⅰ-Ⅱ） （249.50 ng/mL and 305.00 ng/mL， respectively） were markedly lower than those observed in the benign lung disease group （429.16 ng/mL） （P < 0.001）. Univariate and multivariate logistic regression analyses indicated that serum FN could serve as a significant predictor for the presence of NSCLC. The area under the receiver operating characteristic curve （ROC） for serum FN in diagnosing early-stage NSCLC was 0.790， which outperformed CEA （0.618）， SCC （0.653）， and CYFRA21-1 （0.601）. The optimal critical concentration of serum FN for distinguishing early-stage NSCLC from benign diseases was determined to be 347.6 ng/mL， with a sensitivity of 71.93%， surpassing that of CEA （19.30%）， SCC （12.28%）， and CYFRA21-1 （8.77%）. Conclusion Serum FN is significantly downregulated in NSCLC and may serve as a potential biomarker for the early diagnosis of NSCLC.