Objective: The 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.
Methods: A 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.
Results: Among 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).
Conclusions: RRM1 protein may be a valuable predictive factor for gemcitabine/cisplatin adjuvant chemotherapy in NSCLC patients.