Racial disparities in cancer-associated thrombosis.

Race and ethnicity are associated with risk of venous thromboembolism in population-based studies. Blacks/African Americans have a higher incidence, whereas Asians/Pacific Islanders and Hispanics have a lower incidence of venous thromboembolism compared with non-Hispanic Whites. The impact of race/ethnicity on the incidence of cancer-associated thrombosis (CAT), a common complication in patients with malignancy, has not been well defined. Using the California Cancer Registry linked to the California Patient Discharge Dataset and Emergency Department Utilization database, we studied a large, diverse cohort of patients (n = 942 109) from 2005 to 2017 with the 13 most common, first primary malignancies to determine the association between race/ethnicity and incidence of incident and recurrent CAT. Multivariable Cox proportional hazards regression models were performed to determine the effect of race/ethnicity on the risk of overall CAT, specific CAT by location, and recurrent CAT. Blacks/African Americans had a higher incidence of CAT for all tumor types except myeloma, whereas Asians/Pacific Islanders had a consistently lower incidence of CAT compared with non-Hispanic Whites, after adjusting for potential confounders. The main driver for the racial/ethnic differences was incidence of pulmonary embolism. We speculate the association of race/ethnicity with incidence of CAT may be partially because of underlying thrombotic predisposition that varies by ancestry, but we also must consider the impact of social determinants of health on our results.