Effect of increased body mass index on time to tumor progression in metastatic unresectable colorectal cancer patients treated with bevacizumab-based therapy.

Abstract

e14594 Background: High body mass index (BMI) is a well known risk factor in the development and recurrence of several solid tumors including colorectal cancer (CRC). Obesity is associated with increased serum levels of vascular endothelial growth factor (VEGF). Bevacizumab is the main targeted therapy inhibiting tumor angiogenesis by blocking VEGF receptor. We evaluated the effect of BMI on time to tumor progression (TTP) in patients who received bevacizumab based therapy due to advanced colorectal cancer in our institution. Methods: Patients with metastatic colorectal cancer who have been treated with fluoropyrimidine-based combination chemotherapy with bevacizumab were included in the study. Data of patients’ clinical treatment characteristics were obtained from the medical records. The height and weight measured during the initiation of bevacizumab were used to assign the patients to group A (BMI<25 kg/m2) and group B (BMI≥25 kg/m2). The time to tumor progression was defined as the day of initiation of bevacizumab based threpay to the date of first documented progressive disease, the date of death regardless of its course or the date of last follow up if no disease progression or no death occured at this time. Results: 236 patients (median age 57, range 27-79 years) were treated withfluoropyrimidine-based combination chemotherapy with bevacizumab between April 2007 and June 2011. 127 (51.3%) patients had a BMI <25 kg/m2 and 115 (48.7%) patients were found to have a BMI ≥25 kg/m2. One hundred ninety-three patients (82.1%) had first line bevacizumab therapy, and 44 patients (22.8%) had second-line bevacizumab therapy. Tumors of 68.4% of patients in group A and 69,1% of patients in group B progressed during a median 10 months (3-57 months) follow up. The median TTP was 9.5 months in the BMI <25 group and 8.2 months in the BMI >25 group.In multivariate analysis, high BMI (≥25 kg/m2) was associated with significantly shorter TTP (p: 0.002; HR, 1.91; 95% CI, 1.26–2.88). Conclusions: High BMI is a relevant prognostic factor in predicting the time to tumor progression in metastatic colon cancer patients treated with bevacizumab.