Risk of thrombosis in women with malignancies undergoing ovarian stimulation for fertility preservation

Background: Compared with the general population, cancer patients have a higher risk of venous thromboembolism as well as arterial thrombotic events such as stroke, myocardial infarction and peripheral arterial embolism. Therefore a possible concern for women with malignancies undergoing ovarian stimulation for fertility preservation is the increased risk of venous or arterial thrombosis. Methods: In this article, we revised current available literature on the risk of thrombosis in patients with cancer and in women undergoing ovarian stimulation, with the ultimate aim of drawing some indications for preventive measures. Results: Unfortunately, there are no specific data on the risk of thrombosis in women with cancer undergoing ovarian stimulation for fertility preservation. However, the literature suggests that the cancer type and stage, surgery, and chemotherapy all influence the risk of venous and, possibly, arterial thrombosis. Reports of cases of ovarian stimulation in women without malignancies have shown that venous thrombosis rarely occurs unless a pregnancy is achieved, while arterial thrombosis can occur in the absence of pregnancy but is usually only associated with ovarian hyperstimulation syndrome (OHSS). OHSS increases the risk of thrombotic events, but only the early form of the syndrome is relevant for women undergoing fertility preservation. Conclusions: The available evidence on the risks of thrombosis for women undergoing ovarian stimulation for fertility preservation due to a malignancy is reassuring. However the avoidance of the early form of OHSS in women preserving oocytes/embryos due to malignancy is crucial. For these cycles, we advocate the use of a regimen of ovarian stimulation with gonadotrophin releasing hormone (GnRH) antagonists using GnRH agonists to trigger ovulation, an approach that has been shown tomarkedly reduce the risk ofOHSS. Antithrombotic prophylaxis should be administered only to selected subgroups of women such as thosewith other risk factors or thosewho do develop early OHSS.