Nineteen-year, real-world experience of first-line combination chemotherapy in patients with metastatic colorectal cancer: a propensity score analysis from southern Thailand.

Objective: Combination fluoropyrimidine-based chemotherapy is the standard first-line treatment for metastatic colorectal cancer (CRC). We performed a propensity score (PS)-based analysis to report our real-world experience with long-term follow-up of this regimen for metastatic CRC.

Methods: In this retrospective study, 170 patients with newly diagnosed metastatic CRC treated with first-line combination chemotherapy between January 2003 and March 2021 were identified. Cox proportional hazards regression analysis and PS-based approaches with the logistic regression model were adopted, and the results were compared.

Results: The hazard ratio for overall survival (OS) in the oxaliplatin- and irinotecan-based groups was 0.79 (95% confidence interval = 0.56-1.11), and the median OS times in these groups were 16.8 and 13.0 months, respectively. The median time to progression (TTP) for these regimens were 9.0 and 8.9 months, respectively. The objective response rates for the oxaliplatin- and irinotecan-based groups were 42.7% and 34.6%, respectively. OS and TTP did not differ between these regimens in all PS matching models.

Conclusions: First-line treatment using fluoropyrimidine-based chemotherapy regimens in combination with oxaliplatin or irinotecan in patients with metastatic CRC provided comparable efficacy and tolerable toxicity profiles in a real-world setting with long-term follow-up.