BackgroundPrevious studies showed that high and low body mass index (BMI) is associated with worse prognosis in early-stage colorectal cancer (CRC), and low BMI is associated with worse prognosis in metastatic CRC (mCRC). Whether BMI is a prognostic or predictive factor in patients with mCRC is unclear. The aim of the study was to assess the efficacy outcomes according to BMI range in patients with mCRC treated with bevacizumab plus FOLFOX (oxaliplatin, 5-fluorouracyl, folinic acid) chemotherapy regimen. MethodsThe analysis included patients with mCRC receiving bevacizumab plus FOLFOX in the second line treatment. Patients were divided into three study groups according to BMI range: >30kg/m2 (obese patients), ≥ 25 - < 30kg/m2 (overweight patients), <25 (normal weight patients). The median PFS (progression-free survival) and OS (overall survival) of the treated patients was compared based on the BMI range. Analysis of Kaplan-Meier survival, univariate ANOVA, chi-squared tests for categorical variables were used. Analysis of variance (ANOVA) was used to determining the significance of impact on quantitative variables, while for qualitative variables chi-squared tests were used to compare patient from different BMI groups. ResultsThe study included 237 patients with mCRC. The median age of the patients was 65 years (range 34–82). The study group included 54% of males. The median OS and PFS in the study group was 14.6 and 8.8 months, respectively. The comparison of obese vs overweight vs normal BMI range patients revealed a significant difference in mOS (17.5 vs 14.3 vs 13.1 months, p=0.01) and mPFS (9.4 vs 9.1 vs 7.3 months, p=0.03). The regression analysis (Pearson’s linear correlation) also confirmed that there is a statistically significant relationship between the length of OS and PFS and the BMI value. Higher BMI was associated with a better prognosis. The location of the primary lesion on the left side of the colon, less than two metastatic sites and CEA within the normal range before start of the treatment was linked with statistically longer OS. ConclusionsObese and overweight patients presented longer OS and PFS compared with normal weight patients with mCRC cancer treated with bevacizumab plus FOLFOX chemotherapy regimen. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.