Maintenance therapy for colorectal cancer: which regimen and which patients?

The introduction of therapeutic agents such as irinotecan, oxaliplatin, and more recently biologic agents such as vascular endothelial growth factor and epidermal growth factor receptor (EGFR) inhibitors has significantly improved survival of patients with metastatic colorectal cancer. These novel agents have also contributed to added toxicities. Therefore, several studies have evaluated the role of maintenance therapy with less intensive regimens in patients who experienced stable disease or treatment response following induction therapy as a strategy to reduce toxicity and improve quality of life. The success of such strategies, however, requires assurance that their survival would not be compromised. We therefore reviewed studies that have explored the various strategies of treatment de-escalation with an emphasis on survival and toxicity outcomes. Recent studies evaluated the role of maintenance therapy with chemotherapy only, chemotherapy plus bevcizumab, bevacizumab only, and EGFR inhibitors. Current evidence suggests that maintenance strategies offer significant benefit to patients by providing continuous clinical benefit while minimizing the risks associated with continuous therapy. Strategies to improve selection of patients for maintenance therapy versus identifying subgroups of patients that will benefit from a chemotherapy-free interval need to continue to be studied. Finally, as our understanding of the molecular and genetic drivers of colorectal cancer continues to expand, refining these strategies to include more target-specific agents should become more routine.