Comparative Effectiveness of Adjuvant Therapy on Survival in Patients With Metastatic Colorectal Cancer

Postoperative survival outcomes are crucial in treatment decision making. This study aimed to compare the efficacy of adjuvant chemotherapy (AC)-alone with that of chemotherapy + targeted agents (CTA) in patients with metastatic colorectal cancer (mCRC) and to investigate the association between neoadjuvant therapy and survival.

Patients who underwent primary tumor excision and metastasectomy were identified in the Taiwan Cancer Registry from 2010 to 2019. The analysis assessed the influence of adjuvant therapy on survival and examined the interactions between adjuvant therapy types (AC-alone and CTA) and patient characteristics with respect to overall survival.

Overall, 1,728 and 757 patients received AC alone and CTA, respectively. Compared to AC alone, adjuvant CTA yielded similar mortality after surgery [hazard ratio (HR)=1.03; 95% confidence interval (CI)=0.91-1.17] but resulted in marginally reduced mortality among patients treated with neoadjuvant therapy with targeted agents (HR=0.6; 95%CI=0.34-1.05) after propensity score matching. In patients with mCRC, those who received targeted agents preoperatively and postoperatively in combination with AC had the highest mortality rate (HR=1.75; 95%CI=1.33-2.32).

Overall survival is comparable between adjuvant CTA and AC alone, but adjuvant CTA may be more beneficial in patients with mCRC who undergo neoadjuvant therapy with targeted agents.