The impact of initial cancer stage on the incidence of venous thromboembolism: the Scandinavian Thrombosis and Cancer (STAC) Cohort

Background: Absolute measures of the impact of cancer stage on the incidence of venous thromboembolism (VTE) in patients with distinct cancer types have not been investigated in a large population-based cohort study. Objectives: To investigate differences in the incidence rates of objectively confirmed VTE according to the development of cancer in a large population-based cohort study. Cancer type and stage at the time of diagnosis were taken into account. Patients and Methods: The Scandinavian Thrombosis and Cancer Cohort includes data regarding cancer types, stages and objectively confirmed VTE diagnoses among 144 952 participants followed from 1993 to 2012. We studied stage-specific incidence rates of VTE, and calculated incidence rate differences (IRDs) for VTE according to stages in patients with 10 types of solid cancer. Results: During the entire follow-up, 335 VTEs occurred, of which 293 occurred within 5 years. The IRD of VTE in patients with distant metastasis as compared with those with localized disease indicated large variation depending on cancer type. The highest IRD was observed for pancreatic cancer (IRD of 187.0 9 10(-3) person-years [p-y]; 95% confidence interval [CI] - 6.7 to 380.8), and the lowest IRD was observed for prostate cancer (IRD of 3.7 x 10(-3) p-y; 95% CI - 7 to 15.2). Regional spread as compared with localized disease also indicated large variation depending on cancer type; the highest IRD was observed for uterine cancer (IRD of 37.6 x 10(-3) p-y; 95% CI - 23.7 to 99), and the IRDs for breast and prostate cancer were close to zero. Conclusion: More advanced cancer at the time of diagnosis was associated with a higher risk of VTE, but the strength of the associations differed substantially between cancer types.