Survival analysis of colorectal cancer patients treated with first-line modified FOLFOX6 with or without bolus fluorouracil.

Abstract

35 Background: The combination of oxaliplatin, bolus 5-FU (b5FU), infusional 5-FU (5-FUCI), and leucovorin (LV) is the preferred first line treatment option for mCRC. This study evaluates the impact of b5FU on survival in first line therapy for mCRC patients treated with mFOLFOX6. Methods: This was a retrospective chart review of patients ≥ 18 years old with mCRC receiving palliative first line mFOLFOX6 chemotherapy with or without b5FU/ LV from January 1, 2010 through June 1, 2019 at Winship Cancer Institute, Emory University. Data collection included the following: demographics (age, race, gender), disease characteristics (tumor sidedness), microsatellite status, KRAS status, BRAF status, addition of monoclonal antibodies (bevacizumab, panitumumab), ECOG PS, grade 3/4 neutropenic events, addition of growth factors, and treatment delays. The primary endpoint was PFS. The multivariable Cox proportional hazards model for PFS and OS was performed with selected covariates of interest. Results: A total of 252 patients with mCRC met the inclusion criteria. Median follow-up time was 2.4 years. 161 patients (64%) received mFOLFOX6 with b5FU/LV and 91 patients (36%) received mFOLFOX6 with no b5FU/LV. More cycles were delivered in the b5FU group as compared to the non-b5FU group (mean, 4.8 v. 3.8 cycles, respectively; p < 0.001). There were no differences in grade 3 and 4 neutropenic events between groups. Growth factor usage was numerically higher in the bolus group though not significantly different (p = 0.06). No difference was observed in treatment delays between groups (p = 0.83). There was no statistical difference in PFS between treatment groups (1.1 years in the b5FU/LV group v. 0.8 years (95% CI, 0.6-1.0) in the no 5-FU/LV bolus group; p = 0.076). The median OS was 2.5 years in the b5FU/LV group compared to 1.8 years in the no b5FU/LV group (p = 0.012). On univariate analysis, tumor sidedness and performance status were significantly different between groups. On multivariate analysis, none of the variables were significantly different between groups. Conclusions: The omission of the b5FU/LV from mFOLFOX6 does not significantly impact PFS, toxicity or treatment delays. However, OS is significantly shorter when the b5FU/LV is omitted suggesting the clinical importance of maintaining bolus administration with 5-FUCI in the first line palliative treatment of mCRC.