Simon Noble, MBBS, Cardiff University, Cardiff, UK, discusses the pathophysiology and heterogeneity of cancer associated thrombosis (CAT). He highlights how common the condition is, and the need for more understanding of the best way to care for patients with CAT. This interview took place at the International Society of Oncology Pharmacy Practitioners (ISOPP) Symposium 2019, hosted by the British Oncology Pharmacy Association (BOPA), held in London, UK.