Prognostic and safety analysis of capecitabine monotherapy versus CapeOx (capecitabine plus oxaliplatin) in elderly patients with high-risk stage II and stage III MRD-negative colorectal cancer.

[BACKGROUND] Postoperative adjuvant chemotherapy is a cornerstone of treatment for high-risk stage II and stage III colorectal cancer (CRC). However, the optimal regimen for elderly minimal residual disease (MRD)-negative patients remains controversial. This study aimed to compare the efficacy and safety of capecitabine monotherapy versus the CapeOx regimen (capecitabine plus oxaliplatin) in this population.

[METHODS] We conducted a retrospective analysis of 117 elderly patients (aged 65-85 years) with high-risk stage II and stage III CRC who underwent curative surgery and tested MRD-negative. Patients were divided into two groups based on postoperative chemotherapy: capecitabine monotherapy (n=58) and CapeOx (n=59). Baseline characteristics, disease-free survival (DFS), 3-year DFS rates, and adverse events were compared. Propensity score matching (PSM) was used to balance baseline differences, and Kaplan-Meier analysis was performed to assess survival outcomes.

[RESULTS] The median DFS was 31 months in the capecitabine group and 40 months in the CapeOx group (P=0.26). The 3-year DFS rates were comparable (90% 81%, P=0.26). After PSM, the survival outcomes remained similar between the two groups (P=0.73). However, the CapeOx group exhibited significantly higher rates of neurotoxicity (61% 7%, P<0.001), leukopenia (49% 22%, P=0.002), and thrombocytopenia (44% 10%, P<0.001).

[CONCLUSIONS] Capecitabine monotherapy might provide comparable DFS to CapeOx in elderly MRD-negative CRC patients, with better safety profile. MRD status might guide personalized dose-reduction strategies for elderly patients with high-risk stage II and stage III CRC.