The Impact of Omitting 5-FU Bolus From mFOLFOX6 Chemotherapy Regimen on Hematological Adverse Events Among Patients With Metastatic Colorectal Cancer

Background: Metastatic colorectal cancer (mCRC) is often treated with a mFOLFOX6 regimen. The 5-fluorouracil (5-FU) bolus is often omitted from the regimen to reduce the risk of hematological adverse events (AEs) in patients with poor performance status. We aimed to investigate the incidence of hematological AEs in Asian patients with mCRC who were treated with the mFOLFOX6 with and without 5-FU bolus dosing. Methods: This retrospective chart review was conducted at King Chulalongkorn Memorial Hospital, Thailand from June 2021 to June 2022. The primary endpoints were hematological AEs. Secondary endpoints were any AEs. The comparison of continuous data was conducted with an independent t-test. The Chi-squared test was used to compare categorical data. Results: From 110 patients, we found that hematological and non -he-matological AEs of any grade in the two groups were not significant-ly different. However, patients in the bolus arm had a significantly lower absolute neutrophil count (ANC) than those in the non-bolus arm (mean difference = 43.13 (95% confidence interval (CI): 20.74, 65.51), P-value = 0.0002). A subgroup analysis in patients who re-ceived first-line treatment with mFOLFOX6 showed that the bolus arm had a significantly lower ANC (mean difference = 46.01 (95% CI: 19.99, 72.03), P-value = 0.0007). Conclusions: mCRC patients who were treated with bolus 5-FU had lower ANC. The 5-FU bolus omission from the mFOLFOX6 regimen may be required in patients with a high risk of neutropenia.