Purpose: The purpose of this study was to investigate whether obesity affects survival in metastatic colorectal cancer (mCRC) patients treated with bevacizumab combined with chemotherapy.
Methods: A total of 563 patients with mCRC who had received first-line chemotherapy in combination with bevacizumab were studied. Patients were grouped as obese (BMI levels > 30) or non-obese (BMI levels < 30). Progression-free survival (PFS) and overall survival (OS) were analyzed. Primary tumor location was also investigated in terms of PFS and OS.
Results: The median age of the patients was 59 years. The non-obese group had longer PFS than the obese group (P = 0.030). The 2-year survival rate of the non-obese group was also significantly higher (P = 0.036). The median PFS of non-obese patients was significantly longer in Kras wild-type patients (10.1 vs. 8.1 months, P = 0.010). Among patients with left-sided primary tumor location, median PFS and OS were significantly higher in the non-obese group (PFS non-obese, 11.5 months; obese, 8.8 months; P = 0.002) (OS non-obese, 29.4 months; obese, 21.4 months; P = 0.026).
Conclusions: Efficacy of bevacizumab may be lower in obese patients. Among patients with Kras wild-type left-sided tumors treated with bevacizumab-based regimens, the prognosis could be worse for obese patients than that for non-obese patients. There is a need for prospectively designed studies of obese patients to prove the efficacy and dosages of bevacizumab in treatment of mCRC.
Keywords: Bevacizumab; Body mass index; K-ras; Metastatic colorectal cancer; Obesity.