Maintenance treatment in metastatic colorectal cancer: in search of the best strategy.

Over the last 2 decades, the standard fluoropyrimidine-based chemotherapy backbone for metastatic colorectal cancer has been complemented by the addition of novel biological agents, achieving impressive increases in 5-year survival rates. Nonetheless, these new combinations have also entailed increases in toxicity, leading to evaluation of de-escalated chemotherapy regimens and "drug holiday" periods in attempts to reduce side effects and optimise quality of life without impairing efficacy. Here, we review the current and emerging evidence for maintenance schedules with chemotherapy and targeted agents, versus continuous treatment after induction treatment, in metastatic colorectal cancer patients.