Contemporary breast cancer treatment-associated thrombosis

Although cancer-associated thrombosis (CAT) is relatively uncommon in breast cancer compared to other solid cancers, as breast cancer is the most commonly diagnosed cancer in women worldwide, the financial and personal cost of breast cancer associated thrombosis (BrCAT) is significant. This increasing risk of BrCAT over time parallels modern developments in breast cancer management. This review comprehensively reports the evidence for BrCAT in the context of modern breast cancer treatments. The risk of BrCAT is most pronounced within the first 3 months to year of diagnosis. The risk of BrCAT increases with operating time, paralleling the increasing frequency of immediate breast reconstruction. Systemic therapies such as chemotherapy and tamoxifen have well recognised thrombogenic effects, that are exacerbated by surgery and supplementary treatments such as colony-stimulating factors, steroids, and bisphosphonates however risk assessment tools are not designed specifically for this lower-VTE risk cancer. Cyclin-dependent kinases 4 and 6 (CDK4/6) Inhibitors, used in metastatic breast cancer, with trials ongoing in early disease, appear to have a class thrombogenic effect, although there is no increase CAT risk with other breast cancer targeted therapies. Given the numerous prothrombotic treatments facing patients within the first year of diagnosis, from surgery, chemotherapy, targeted therapies and endocrine therapy, a more personalised approach considering the additive effects of each individual patient's pathway, as well as their pre-existing risk factors, needs to be considered.