Thrombotic events in metastatic colorectal cancer patients treated with leucovorin, fluorouracil and irinotican (FOLFIRI) plus bevacizumab

Objective: To determine the incidence and risk factors for thrombotic events (TEs) in patients with metastatic colorectal cancer (mCRC) who received bevacizumab (BV) and FOLFIRI (leucovorin, fluorouracil and irinotican) compared to FOLFIRI alone.

Methods: Single institution retrospective study of 450 mCRC patients who received either BV plus FOLFIRI or FOLFIRI alone between April 2004 and August 2012. Demographics, TE risk factors, and treatment data were abstracted from patients' records. Multivariate analysis was used to identify factors that contributed to thromboembolism.

Results: Two-hundred-sixty-one mCRC patients received BV plus FOLFIRI [64.8% males, mean body mass index (BMI) of 27.6] compared to 189 control patients who received FOLFIRI alone (61.9% males, BMI 27.2). The incidence of TEs was 14.9% in the BV plus FOLFIRI group, compared to 15.9% in the control group. Multivariate analysis controlling for age, BMI, gender, malignancy, metastatic sites, line of treatment, and risk factors did not suggest a significant increase in the risk of TE with the addition of BV (OR =0.83 95% CI: 0.40-1.70; P=0.602). No difference in the site of TEs was observed between the treatment groups. The only statistically significant risk factor for thrombosis in the FOLFIRI plus BV group was increased BMI (OR =1.05; 95% CI: 1.01-1.10; P=0.01).

Conclusions: This study does not support a significant increase in the risk of TE in patients with mCRC who received BV in addition to FOLFIRI. Increased BMI may be a risk factor for thrombosis in patients treated with BV.