ObjectiveTo investigate the value of serum soluble CD146 (sCD146) in determining acquired epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) resistance in lung adenocarcinoma.MethodsA total of 144 lung adenocarcinoma EGFR sensitive patients in People’s Hospital of Zhengzhou University diagnosed from January 2016 to December 2016 were recruited in the study. According to the different time of taking drugs, the patients were divided into a non-medication group (31 cases), a 1 to 3 month treatment group (25 cases), a 4 to 6 month treatment group (19 cases), a 7 to 12 month treatment group (25 cases), a drug-resistant group (24 cases), and a nonresistant group up to 1 year of treatment (20 cases). The serum levels of sCD146, carcinoembryonic antigen (CEA) and neuron-specific enolase (NSE) were measured by ELISA and chemiluminescence and compared between different period of medication. The relationship of serum sCD146 with tumor markers (CEA, NSE) and tumor related clinical parameters (age, gender, tumor stage, metastasis, tumor diameter, number of the lesions) were analyzed.ResultsThe serum sCD146 level was minimum in the non-medication group that did not receive pioglitazone treatment, highest in the 1 to 3 month treatment group (early treatment period), and declined with duration of medication until resistance occurred without significant difference (P>0.05). The level of sCD146 of the drug-resistant group was significantly lower than that of all nonresistant groups, with significant difference (allP<0.05), but still higher than that of the non-medication group (P<0.05). The serum sCD146 levels in the nonresistant patients with medication over 1 year and within 1 year were similar (P>0.05), and significantly higher than the non-medication group and drug-resistance group (allP<0.05). The serum CEA levels did not differ significantly between 6 groups (P>0.05). The serum NSE level of the 4 to 6 month treatment group was lower than that of the 7 to 12 month treatment group (P<0.05), but both in the normal reference range. The NSE levels did not differ in any other groups (P>0.05). Serum sCD146 was associated with metastasis (P<0.05), but not associated with serum CEA or NSE, nor with sex, age, tumor staging, tumor diameter or lesion number (allP>0.05).ConclusionsCD146 may be involved in the mechanism of TKI killing tumor cells and the mechanism of TKI resistance, and may be a serological marker for monitoring the efficacy of TKI and judging the resistance of TKI.