Optimizing the treatment sequence from second-line to third-line therapy in patients with metastatic colorectal cancer

In clinical trials of metastatic colorectal cancer, progressive disease after second-line therapy is often defined according to Response Evaluation Criteria in Solid Tumors criteria. In the clinic, however, disease progression can be identified through a composite of factors, including new lesions, carcinoembryonic antigen level, and symptoms such as pain and fatigue. It is optimal to switch to third-line treatment before the patient's performance status deteriorates. In the third-line setting, regorafenib and trifluridine tipiracil are approved for the treatment of patients with metastatic colorectal cancer who are refractory to standard chemotherapy. Both of these treatments are associated with prolonged overall survival and progression-free survival in heavily pretreated patients. Data suggest that a chemotherapy break may be beneficial in patients with metastatic colorectal cancer. Some data suggest that treatments beyond the third-line setting might also improve outcome.