Objectives: Colorectal cancer (CRC), is one of the leading causes of mortality worldwide and is the second most common cancer in developed countries. Bevacizumab, a recombinant humanized monoclonal antibody to vascular endothelial growth factor has been approved for use in combination chemotherapy for the first or second-line treatment of patients with metastatic colorectal cancer. The risk of arterial thromboembolism was found to be higher in the patients received combination treatment with bevacizumab. Mean platelet volume is a parameter that measures the platelet size and is defined as a marker of platelet reactivity. Methods: A total of 108 patients from medical oncology department of Acibadem Kayseri Hospital with metastatic colorectal cancer and receiving first line combination treatment with bevacizumab were included in this study. Age, gender, comorbidity status, body mass index, smoking status and the type of chemotherapy combination were also enrolled. Results: At the 3rd month of the treatment, mean platelet volume levels were found to be increased in the total patient group from 8.98±0.16 to 9.28±0.14 and this was statistically significant (p<0.0001). Also there were significant increases in mean platelet volume values in the patients with normal body mass index, non-smokers and the patients who did not have any comorbidity. Platelet values did not change in any of the subgroups except for the patients over 65 years of age. Conclusion: Based on the results of our study, we think that bevacizumab induced thrombosis can be achieved through MPV increase. The fact that MPV increases especially in the patients without comorbidity, in non-smokers and in normalweight patients, suggest that bevacizumab leads to a condition that causes MPV increase regardless of these factors and so special attention should be paid to MPV values in the follow-up of the patients receiving chemotherapy protocols containing bevacizumab. Due to the number of physiological variables affecting the platelet size and poor standardization of mean platelet volume measurement, properly designed clinical studies -with more personalized reference ranges and better methodological standardization- are needed to make it a reliable parameter for differential diagnosis and prognostic identification of thrombosis in the metastatic colorectal cancer patients receiving bevacizumab combination treatment. Keywords: Bevacizumab, colorectal cancer, mean platelet volume, thromboembolic events
Corresponding Author: Karagoz H.