Pseudoprogression; discussion of the concept of pseudoprogression on the characteristics of tomographic changes in liver metastases of colorectal cancer patients receiving bevacizumab therapy

In this study, we aimed to investigate the concept of pseudoprogression in colorectal cancer patients with liver metastases receiving bevacizumab treatment by considering the changes in the shape, size, and density of liver metastases by abdominal Computed Tomography (CT) scans taken before and after treatment. This study is a retrospective evaluation of 16 patients with metastatic colorectal cancer treated with 5-fluorouracil, leucovorin, irinotecan and bevacizumab and is based on computed tissue analysis of the dominant liver lesion at baseline and 2 months after chemotherapy. The borders of all metastatic lesions observed in the livers of patients treated with bevacizumab after adjuvant chemotherapy were sharpened, the size of some lesions remained the same while others increased, and the density of most metastatic lesions decreased. In our study, we concluded that the evaluation of response to treatment based only on size and number should be avoided by noting a pseudoprogression in liver metastases that shows an increase in size but no progression on clinical/laboratory and follow-up images.