Maintenance strategy in metastatic colorectal cancer: A systematic review

Purpose: Colorectal cancer is the third most common cancer in men and second in women, estimated to cause 694,000 deaths worldwide in 2012. Although 5-year survival rate of CRC has increased, inoperable metastatic colorectal cancer (mCRC) is almost always fatal. The aim of this systematic review is to outline the maintenance strategies that increase the chance and duration of survival with less toxicity and sustained quality of life. Design: Literature search in PubMed, in American Society of Clinical Oncology (ASCO) Annual Meetings and in ASCO Gastrointestinal Symposia and European Society for Medical Oncology (ESMO) Congresses was performed. Studies conducted in adult patients were written in English language and were published in peer-reviewed journals as phase II or III randomized controlled trials (RCTs) comparing continuous chemotherapy to intermittent chemotherapy, each with or without maintenance therapy was included along with at least one of the outcomes of interest. Results: Twenty randomized controlled trials and systematic reviews were included from Medline search, together with 4 abstracts from ASCO meetings and 2 abstracts from ESMO meetings. Conclusion: Existing evidence-based data show that prolonged progression free survival (PFS) can be achieved with less toxic regimens compared to complete drug holidays or continued treatment. However, the impact of maintenance on overall survival is less clear. The specific data for maintenance with biological agents are evolving, while in general fluoropyrimidine based maintenance with bevacizumab is better than Bev alone or observation for PFS. Data regarding Cetuximab maintenance are less pronounced than that of Bev maintenance. Preliminary data show that erlotinib-Bev combination may be of benefit as maintenance. Although maintenance may provide significant clinical benefit in clinical studies, the optimal strategy should still be individualized.