Effectiveness of adjuvant chemotherapy in patients with Stage II colorectal cancer: A multicenter retrospective study

Background: Adjuvant chemotherapy (ACT) for patients with Stage II colorectal cancer (CRC) is an area of controversy in oncology. International guidelines recommend the use of ACT in patients with specific high-risk features. This study aimed to investigate the effectiveness of ACT in improving survival in patients with and without high-risk features. Materials and Methods: A total of 225 patients with Stage II CRC who underwent primary tumor resection were included in this study. Patients with one or more high-risk features including T4 tumor, poor differentiation, lymphovascular invasion, perineural invasion, bowel obstruction, local perforation, positive resection margins, or suboptimal lymph node sampling (fewer than 12 nodes) were classified as high risk. The survival analysis was performed between patients who only received curative surgery and those received single-agent (5-fluorouracil [5-FU] and leucovorin [LV] or capecitabine) or multiagent ACT (oxaliplatin and 5-FU + LV or oxaliplatin and capecitabine). Results: The 5-year overall survival (OS) rate was 88.4%, and the 5-year disease-free survival (DFS) rate was 80.4%. The 5-year OS and DFS rates improved insignificantly with ACT (89.8% vs. 81.2%, P = 0.59 and 81.3% vs. 74.6%, P = 0.41, respectively); however, multiagent ACT results to inferior 5-year OS and DFS compared to single-agent ACT (82.1 vs. 92.8%, P = 0.14 and 70.1% vs. 86%, P = 0.07, respectively). ACT was associated with insignificant improved OS and DFS in both high-risk and low-risk groups, but high-risk patients who received multiagent ACT had a significant inferior OS and DFS in comparison with those received single-agent ACT. T4 tumor and obstruction were independent poor prognostic factors affecting OS and DFS. Conclusion: In our population, the improvement of OS and DFS with ACT was not statistically significant in high-risk and low-risk patients with Stage II CRC.