Is CA19-9 effective in predicting chemotherapeutic response in patients with synchronous liver metastases with colorectal cancer?

Evaluation of response to chemotherapy in colorectal cancer patients with synchronous liver metastases is important in terms of treatment management. In this Letter to the Editor, several issues in the article are discussed. For the comparison of carbohydrate antigen 19-9 (CA19-9) values referenced in the study, the patient group was not matched for cancer stage. Therefore, it may be more appropriate to select and compare CA19-9 values in patients with same-stage cancer.