Should we still be using bolus 5-FU prior to infusional regimens in gastrointestinal cancers? A practical review.

5-fluorouracil (5-FU), a pyrimidine analogue with antimetabolite activity, is one of the most widely used drugs in Oncology and many different regimens have been described regarding its use. Nowadays, the modified de Gramont is the most popular schedule of 5-FU to treat gastrointestinal cancers and may be given either alone or combined with irinotecan, oxaliplatin and monoclonal antibodies. The true clinical value of bolus 5-FU right before infusional regimens remains to be determined since no randomized trials have addressed this issue. This manuscript aims to review the history of 5-FU, its mechanism of action and the data exploring the role of bolus 5-FU. © The Japan Society of Clinical Oncology 2021.