(43) Comparative Effectiveness of Adjuvant Chemotherapy Versus Chemotherapy Plus Targeted Therapy After Resection of Both Primary Tumor and Metastases in Patient with Colorectal Cancer

Publication Number: 717

Background: Achieving primary tumor resection and metastasectomy might be important and most beneficial for a great proportion of patients with metastatic colorectal cancer (mCRC) in clinical settings. To determine the clinical decision, it is important to assess the difference in survival outcomes of adjuvant therapy between chemotherapy (CT) alone and CT plus targeted agents (TA) after surgery.

Objectives: To assess the effectiveness of adjuvant therapy with CT alone and CT plus TA in mCRC patients on survival outcome, and examine the interaction between neo-adjuvant therapy and survival outcome among mCRC patients receiving adjuvant CT plus TA or not, using the Taiwan population databases.

Methods: Using the Taiwan National Health Insurance Database (NHID) and Taiwan Cancer Registry, we identified patients with mCRC who received adjuvant therapy from January 1st, 2009, through December 31st, 2019. Overall survival of patients who received primary tumor resection and metastasectomy was assessed after receiving adjuvant CT alone or CT plus TA. The multivariable analysis for survival outcome after adjuvant therapy was performed via Cox regression. We matched CT alone to CT plus TA group by propensity scores (PS) matching and weighting 2.69 (1.95-3.69).

Results: Overall, 697 patients with mCRC were enrolled in our study; 429 and 268 patients received CT alone or CT plus TA therapy, respectively. Compared with adjuvant CT alone, adjuvant CT plus TA resulted in similar mortality among mCRC patients after primary tumor resection and metastasectomy (hazard ratio [HR]= 1.00; 95% CI, 0.82–1.22), whereas adjuvant CT plus TA did marginally reduce the mortality rate among patients treated with neo-adjuvant with TA (HR= 0.51; 95% CI, 0.25–1.04) after PS weighting. Among patients treated adjuvant CT alone, neo-adjuvant CT with TA was associated with higher mortality (HR=2.69; 95% CI, 1.95–3.69) than patients who received neo-adjuvant CT alone.

Conclusions: Although overall results demonstrate survival is similar between adjuvant CT plus TA and CT alone, our findings suggest that the adjuvant CT plus TA would improve OS benefit compared to adjuvant CT alone if mCRC patients received neo-adjuvant CT plus TA. This would underscore the importance of stratification by neo-adjuvant CT with TA or not in applying current treatment guidelines and for future clinical trials.