Complete radiological response of colorectal liver metastases after chemotherapy: what can we expect?

Missing metastases, also called vanishing or disappearing liver metastases, concern about 5% of patients with colorectal liver metastasis undergoing chemotherapy, and this phenomenon is likely to become more frequent in the near future, with the widespread use of highly efficient chemotherapy. As their definition is highly dependent on the quality of initial imaging, a DLM on preoperative computed tomography scan should be systematically confirmed by a second imaging modality, ideally magnetic resonance imaging. It is important to note that a complete clinical response does not mean a complete pathologic response. Currently, there are no absolute criteria of a complete pathologic response. However, treatment with neoadjuvant and adjuvant hepatic arterial infusion in patients <60 years old with an initially low carcinoembryonic antigen level that normalizes under chemotherapy and who have no detectable lesion on both computed tomography and magnetic resonance imaging is probably more likely to yield a complete pathologic response. Whatever their treatment, patients with DLM run a high risk of recurrence that could be decreased with the use of HAI. Despite a high recurrence rate, the overall 5-year survival rate of patients with DLM ranges from 40 to 80%. Having a DLM should no longer be a contraindication to hepatic surgery since long-term survival is expected in these highly chemosensitive patients. The use of adjuvant HAI in addition to efficient systemic chemotherapy could reduce the risk of hepatic relapse.