PURPOSE: To describe the dosing patterns of regorafenib in a real-world population of patients with metastatic colorectal cancer (mCRC) in a routine clinical practice setting in Spain, focusing on the starting dose of regorafenib. METHODS: An observational, retrospective, multicenter study that included patients ≥ 18 years old who had histologically documented mCRC and who had initiated treatment with regorafenib since January 2017. Post hoc categorization of dosing patterns revealed the following: initial dose <
160 mg and dose escalation, initial dose <
160 mg and maintenance, initial dose equal to 160 mg and maintenance, and initial dose equal to 160 mg and dose reduction. RESULTS: Most patients (152/241, 63.8%) initiated treatment with regorafenib at doses <
160 mg. There was large variation in the starting dose of regorafenib over time: in 2017, most patients (59%) initiated regorafenib at a dose of 160 mg, this proportion decreased to 6% in 2021. There were no significant differences in the median progression-free survival according to the regorafenib dose patterns during the first two cycles. The proportion of patients who reported at least one adverse event (AE), had a grade 3-4 AE or had an AE leading to dose reduction was greater in the group of patients who received an initial dose equal to 160 and reduction. CONCLUSIONS: Our results indicate that physicians in Spain have gradually adopted a dose-escalation approach during cycle 1, which is a common practice for starting treatment with a reduced dose (<
160 mg/day), a strategy that seems to improve tolerability while maintaining efficacy. TRIAL REGISTRATION: Not applicable.