Patients with cancer are at a high risk of venous thromboembolism (VTE)—in fact, it’s one of the leading causes of death in patients who receive systemic therapy for cancer. But as cancer treatment has evolved, have the incidence and risk of VTE changed too?
Researchers from Veterans Affairs Boston Healthcare System in Massachusetts conducted a study with 434,203 veterans to evaluate the pattern of VTE incidence over 16 years, focusing on the types of cancer, treatment, race and ethnicity, and other factors related to cancer-associated thrombosis (CAT).
In contrast with other large population studies, this study found the overall incidence of CAT remained largely stable over time. At 12 months, the incidence was 4.5%, with yearly trends ranging between 4.2% and 4.7%. “As expected,” the researchers say, the subset of patients receiving systemic therapy had a higher incidence of VTE at 12 months (7.7%) than did the overall cohort. The pattern was “particularly pronounced” in gynecologic, testicular, and kidney cancers, where the incidence of VTE was 2 to 3 times higher in the treated cohort compared with the overall cohort.
Cancer type and diagnosis were the most statistically and clinically significant associations with CAT, with up to a 6-fold difference between cancer subtypes. The patients at the highest risk of VTE were those with pancreatic cancer and acute lymphoblastic leukemia.
Most studies have focused only on patients with solid tumors, but these researchers observed novel patterns among patients with hematologic neoplasms. Specifically, a higher incidence of VTE among patients with aggressive vs indolent leukemias and lymphomas. This trend, the researchers say, may be associated in part with catheter-related events.
Furthermore, the type of system treatment was associated with the risk of VTE, the researchers say, although to a lesser extent. Chemotherapy- and immunotherapy-based regimens had the highest risk of VTE, relative to no treatment. Targeted and endocrine therapy also carried a higher risk compared with no treatment but to a lesser degree.
The researchers found significant heterogeneity by race and ethnicity across cancer types. Non-Hispanic Black patients had about 20% higher risk of VTE compared with non-Hispanic White patients. Asian and Pacific Islander patients had about 20% lower risk compared with non-Hispanic White patients.
Male sex was also associated with VTE. However, “interestingly,” the researchers note, neighborhood-level socioeconomic factors and patients’ comorbidities were not associated with CAT but were associated with mortality.
Their results suggest that patient- and treatment-specific factors play a critical role in assessing the risk of CAT, and “ongoing efforts to identify these patterns are of utmost importance for risk stratification and prognostic assessment.”