A Study of the S-1 or Capecitabine as First-line Regimen in Patients with Metastatic Colorectal Cancer: A Real World Study

Objectives: To compare the 2-year overall survival (OS) rate and safety between patients using S-1 and capecitabine in the first-treatment of metastatic colorectal cancer in the real clinical setting. Methods: In this retrospective cohort study, patients satisfying the following criteria were identified from 10 centers in China. The 2-year OS rate and safety were assessed. The propensity score matching (PSM) was used to control basic characteristics of the two groups to balance the processing bias and confoundings. Results: A total of 1367 patients were identified, 824 patients accepted capecitabine and 546 patients accepted S-1. After PSM, 533 eligible patients were included in each group without statistical significance in age, sex, BMI, KPS score and comorbidities. The 2-year OS rate between two groups was without significant statistical difference (61.9% vs. 62.9%, p=0.4295). The subgroup analysis showed that the 2-year OS rate had no significant difference between men and women, younger and older than 60 years old, different metastatic sites, different chemotherapy courses between S-1 and capecitabine groups. The hematological adverse events were all without statistical difference between two groups, but the incidence of diarrhea (16.4% vs. 23.6%, p=0.0018) and hand-foot syndrome (28.7% vs. 46.7%, p<0.001) in S-1 group were lower than those in the capecitabine group. Conclusions: Compared to capecitabine, S-1 had a similar 2-year OS rate but had a lower incidence of adverse events in the real clinical setting. So, S-1 could be a good choice in the first-treatment of patients with metastatic colorectal cancer in China.