The aim of the present study was to assess the effects of gefitinib chemotherapy on the serum levels of miR-7 in patients with non-small cell lung cancer (NSCLC). A total of 126 patients were enrolled in the present study (stage I–II, n=54 and stage III–IV, n=72). Patients with stage I–II NSCLC underwent surgery in combination with gefitinib chemotherapy, whereas only gefitinib chemotherapy was administered to patients with stage III–IV disease. Serum levels of miR-7 before and after treatment were measured with quantitative polymerase chain reaction using fluorogenic probes, and miR-7 positivity and scoring in resected specimens were determined by immunohistochemistry. The number of miR-7-positive cases and the number of cases with higher miR-7 scores were significantly lower among patients with stage I–II NSCLC than those with stage III–IV disease. Additionally, serum levels of miR-7 before and after intervention were lower in stage I–II than in stage III–IV NSCLC cases. Serum levels of miR-7 after treatment were significantly lower than those before intervention in the two groups. The treatment success rate was significantly higher in miR-7-negative patients than in miR-7-positive patients in the two patient groups. Adverse event rates in miR-7-negative and -positive patients were comparable between the groups. Among those with stage III–IV NSCLC, the survival rate of miR-7-positive patients was significantly lower than that of miR-7-negative patients. Conversely, among those with I–II NSCLC, the progression-free survival and median survival time of miR-7-positive patients were significantly lower than those of miR-7-negative patients. Our findings suggest that serum and expression levels of miR-7 in the tissue were closely associated with tumor staging and the therapeutic effects of gefitinib in NSCLC.

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