Optimizing palliative treatment of metastatic colorectal cancer in the era of biologic therapy

Over the past decade, new cytotoxic and biologic therapies beyond the old standard-of-care, biomodulated fluorouracil (5-FU), have become available for the treatment of metastatic colorectal cancer (mCRC). The introductions of irinotecan (Camptosar), oxaliplatin (Eloxatin), and bevacizumab (Avastin) have prolonged survival, but the optimal use of these new therapies remains to be determined. Issues remain regarding management of toxicities, treatment of elderly patients or those with poor performance status, and the duration of treatment with front-line therapy. This article reviews recent and ongoing studies of newer therapies in an effort to determine the best use of these drugs in the treatment of mCRC. Current data support the front-line use of bevacizumab added to either 5-FU/leucovorin alone or 5-FU/leucovorin in combination with oxaliplatin (FOLFOX/bevacizumab) or irinotecan (FOLFIRI/bevacizumab). If oxaliplatin is used in first-line therapy, oxaliplatin should be discontinued before the development of severe neurotoxicity and be reintroduced or replaced with irinotecan on disease progression. Definitive conclusions on the sequence and duration of front-line therapy and the most effective strategy to ameliorate toxicity await results of ongoing prospective clinical trials.