Methods of overcoming treatment resistance in colorectal cancer.

Metastatic colorectal cancer remains a lethal disease with a poor prognosis in the majority of patients. Multiple drug combinations have been developed in recent years that have significantly improved response rates and overall survival however resistance to these drugs is inevitable. Novel agents are currently being developed and participation in clinical trials should be encouraged. In the absence of other treatment options in a patient with good performance status, there is compelling evidence for re-challenging with previously administered agents in different combinations. The aim of this review is to discuss mechanisms of resistance and methods to overcome treatment resistance in patients with metastatic colorectal cancer who are refractory to 5-FU, irinotecan, oxaliplatin, cetuximab and bevacizumab therapy.