OBJECTIVEThe purpose of this study was to investigate the relationship between the expression of ribonucleotide reductase subunit M1 (RRM1) protein and the efficacy of gemcitabine/cisplatin (GP) adjuvant chemotherapy in postoperative non-small cell lung cancer (NSCLC) patients.

METHODSA total of 68 patients with NSCLC after radical surgery were included in this study. The expression of RRM1 protein in tumor specimens was assayed by streptavidin-peroxidase (SP) immunohistochemistry retrospectively. Correlation between the expression of RRM1 protein and the efficacy of GP chemotherapy was analyzed. Disease-free survival rate was taken as the main outcome measure.

RESULTSAmong the 68 patients, 31 cases had recurrence or metastasis. The expression rate of RRM1 was 54.4%. The 1-year and 3-year disease-free survival rates were 82.7% and 61.5% for patients with RRM1-negative expression, and 78.1% and 36.8% for patients with RRM1-posivive expression, respectively (P = 0.044). In the subgroup analysis of stage IB cases, the 1-year and 3-year disease-free survival rates were 100% and 82.3% for patients with RRM1-negative expression, and 84.5% and 24.6% for patients with RRM1-positive expression, respectively (P = 0.047). In the analysis of squamous cell carcinoma subgroup, the 1-year and 3-year disease-free survival rates were 92.3% and 83.7% for patients with RRM1-negative expression, and 83.1% and 43.9% for patients with RRM1-posivive expression, respectively (P = 0.005). Univariate analysis and multivariate analysis indicated that smoking history, pathological type, clinical stage and expression of RRM1 significantly influenced the therapeutic efficacy (P < 0.05).

CONCLUSIONSRRM1 protein may be a valuable predictive factor for gemcitabine/cisplatin adjuvant chemotherapy in NSCLC patients.