Retrospective analysis of the impact of dose delay and reduction on outcomes of colorectal cancer patients treated with FOLFIRI‑based treatment

OBJECTIVES: To determine the relationship between chemotherapy dose delay/reduction with progression-free survival (PFS) and overall survival (OS) in colorectal cancer patients treated with FOLFIRI based first-line chemotherapy in real-world retrospectively study. METHODS: We identified 144 eligible patients with advanced CRC who received FOLFIRI as first-line based treatment. The study protocol was submitted to the institutional review board and was exempted. Dose delay was defined as an average delay of more than 3 days (>3 days vs. ≤3 days) from the intended date. Dose reduction (actual dose/standard dose * 100%) ≤85% was considered as chemotherapy reduction in the chemotherapy dose relative to the standard (mg/m(2)) regimen for all cycles. Relative dose intensity (RDI) ≤80% was described as chemotherapy reduction. OS and PFS were measured using Kaplan–Meier and Cox proportional hazard models. RESULTS: There were 114 patients with chemotherapy dose delay (dose delay >3 days). PFS of patients without dose delay had better survival than patients with dose delay (p = 0.002). There were 28.47% patients treated with dose reduction of 5-Fu. PFS and OS were better in patients without 5-Fu dose reduction than in patients with 5-Fu dose reduction with p values of 0.024 and <0.001, respectively. Patients with high 5-FU RDI had better PFS than patients with low 5-FU RDI (p < 0.001). While, there was no statistical difference in OS between the two groups. Then we stratified the analysis by age. In <65 years cohort, both PFS and OS were better in patients with high 5-Fu RDI than in those with low 5-Fu RDI (p < 0.001, p = 0.005, respectively). But, in ≥65 years cohort, OS were better in patients with low 5-Fu RDI than in those with high 5-Fu RDI (p = 0.025). Moreover, both dose reduction and RDI of irinotecan had no statistically significant difference in both PFS and OS. CONCLUSION: In the advanced colorectal cancer patients who received FOLFIRI based treatment as first-line regimen, chemotherapy dose delay and reduction dose of 5-Fu were associated with worse survival, especially among patients younger than 65 years.