A cohort study on blood coagulation in childhood cancer survivors

Cancer survivors are at an increased risk of thromboembolism compared to the general pediatric population. Anticoagulant therapy decreases the risk of thromboembolism in cancer patients. We hypothesized that pediatric cancer survivors are in a chronically hypercoagulable state compared to healthy controls. Children who survived for more than five years from cancer diagnosis at the UT Health Science Center at San Antonio Cancer Survivorship Clinic were compared to healthy controls. The exclusion criteria were recent NSAID use or a history of coagulopathy. Coagulation analysis included platelet count, thrombin-antithrombin complexes (TAT), plasminogen activator inhibitor (PAI), routine coagulation assays, and thrombin generation with and without thrombomodulin. We enrolled 47 pediatric cancer survivors and 37 healthy controls. Platelet count was significantly lower in cancer survivors at a mean of 254 x 109/L (95%CI: 234-273 x 109/L) compared at 307 x 109/L (283-331 x 109/L) in healthy controls (p < 0.001), although not outside the normal range. Routine coagulation assays showed no differences, except for a significantly lower prothrombin time (PT) in cancer survivors (p < 0.004). Cancer survivors has significantly elevated biomarkers of the procoagulant state, such as TAT and PAI, compared to healthy controls (p < 0.001). A multiple logistic regression model controlling for age, BMI, gender, and race/ethnicity documented that a low platelet count, short prothrombin clot time, and higher procoagulant biomarkers (TAT and PAI) were significantly associated with past cancer therapy. Survivors of childhood cancer have a persistent procoagulant imbalance for more than five years after diagnosis. Further studies are needed to establish whether procoagulant imbalance increases the risk of thromboembolism in childhood cancer survivors.