Effect of cetuximab combined with chemotherapy in treating metastatic colorectal cancer and its prognostic analysis.

Purpose: To explore the efficacy and safety of cetuximab plus chemotherapy in the treatment of metastatic colorectal cancer (mCRC), and to analyze the possible factors affecting the prognosis.

Methods: Clinical data were collected from 136 patients who were definitely diagnosed with mCRC in our hospital from January 2015 to December 2016, and whose genetic test showed wild-type (WT) Kirsten Ras (KRAS), and they were randomly divided into two groups and underwent cetuximab plus chemotherapy (n=68, Cetuximab group) or only chemotherapy (n=68, Chemotherapy group). The clinical short-term efficacy, incidence of adverse reactions and quality-of-life score of patients were compared between the two groups, and the survival and disease progression were recorded during follow-up.

Results: After treatment, there were statistically significant differences between Cetuximab group and Chemotherapy group regarding objective response rate (ORR) and disease control rate (DCR) [69.1% (47/68) vs. 60.3% (41/68), 85.3% (58/68) vs. 79.4% (54/68)] (p=0.282, p=0.368). After treatment, Cetuximab group exhibited notably higher physical and emotional functioning scores on the function subscale [(92.53±12.11) points vs. (88.39±11.78) points, p=0.045, (94.63±12.72) points vs. (89.06±12.40) points, p=0.011] and rash score on the symptom subscale [(39.35±9.73) vs. (35.51±9.09) points, p=0.019)] than Chemotherapy group. According to the follow-up results, the median overall survival (mOS) and median progression-free survival (mPFS) were 25.1 months and 9.5 months, respectively, in Cetuximab group, and 19.8 months and 7.4 months, respectively, in Chemotherapy group. It was found through log-rank test that the OS and PFS in Cetuximab group were dramatically longer than those in Chemotherapy group (p=0.038, p=0.013). Based on the results of multivariate analysis, poor tumor differentiation was an independent risk factor for the mPFS and mOS of patients [hazard ratio (HR) =0.894, 95% confidence interval (CI) (0.581-0.987), p=0.034, HR=0.907, 95%CI (0.603-0.960), p=0.041].

Conclusion: Cetuximab plus chemotherapy has exact efficacy in treating mCRC, and it results in a higher long-term survival rate and a lower disease progression rate than chemotherapy alone, improves the quality of life of patients and produces tolerable adverse reactions. Besides, poor tumor differentiation is an independent risk factor for the mPFS and mOS of patients.