Association of antibiotic exposure with the mortality in bevacizumab-treated metastatic colorectal cancer: A secondary analysis from Dryad database.

Abstract

e15609 Background: Colorectal cancer (CRC) is one of the most diagnosed cancers and the second leading cause of cancer-related death worldwide. Globally, more than 1.8 million people are diagnosed of colorectal cancer (CRC) in 2018. In advanced CRC patients, bevacizumab plus 5-fluorouracil-based or platinum-based therapy has become one of the standard first-line chemotherapy regimen. A recent study also found that antibiotic exposure could be inversely associated with the mortality in metastatic colorectal cancer (mCRC) patients treated with bevacizumab. However, subgroup analysis of this study was no sufficient. Therefore, we conducted a secondary analysis based on the data of this study from Dryad database. Methods: In this retrospective cohort study, 147 mCRC patients treated with bevacizumab were included. All data was obtained from Dryad database (https://doi.org/10.5061/dryad.ft5sk66). Patients were divided into follow subgroups: (1) left colon vs right colon; (2) BMI < 18.5 vs BMI 18.5-24 vs BMI≥24;(3) Age < 45 vs Age≥45, (4) no surgery vs palliative surgery vs radical surgery, (5) bevacizumab plus FOLFIRI vs bevacizumab plus capeOX/FOLFOX vs bevacizumab plus other chemotherapy regimen. Specific survival of each subgroup was analyzed through the Kaplan-Meier curve, and the survival curves of the variables were compared using the log-rank test. Results: Survival analysis found no statistically significant differences of the cumulative survival rates between left colon cancer and right colon cancer, (58.9% vs 62.5%, respectively; χ2 = 0.043, P = 0.836), groups of different BMI (57.9% of BMI < 18.5 vs 55.2% of 18.5≤BMI < 24 vs 70.7% of BMI ≥24，χ2 = 3.026, P = 0.220), Age < 45 group and Age≥45 group (54.8% vs 61.2%, respectively; χ2 = 0.001, P = 0.976), surgical treatments (No surgery 59.0% vs Palliative surgery 57.6% vs Radical Surgery 61.3%; χ2 = 1.885, P = 0.390), as well as groups of different chemotherapy regimens (66.7% of FLOFIRI vs 52.0% of CapeOX/FOLFOX vs 59.9% of others; χ2 = 1.572, P = 0.456). Conclusions: Based on the data from this study, we found that different sites of colon cancer, age, BMI, different surgical treatments, and different chemotherapy regimens did not affect the survival outcome of patients with mCRC treated with bevacizumab after antibiotic exposure. Subsequent studies with larger sample size are still needed to further elaborate the effects of different antibiotics on survival outcomes.