Incidence of Newly Diagnosed Cancer After Cerebral Venous Thrombosis.

Importance: Active cancer is a risk factor for cerebral venous thrombosis (CVT), but whether CVT is associated with occult cancer is unknown. Objective: To evaluate the incidence of newly diagnosed cancer after CVT. Design, Setting, and Participants: This population-based cohort study used data from the Dutch Hospital Discharge Registry from January 1, 1997, to July 1, 2020. Analyses were conducted between June 2023 and April 2024. Patients admitted with a first-ever CVT were included. Patients with a history of cancer or diagnosed with cancer during hospitalization for CVT were excluded. Exposure: CVT was identified using International Classification of Diseases, Ninth Revision (ICD-9) and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes. Main Outcomes and Measures: The main outcome was cumulative incidence of cancer after CVT. Standardized incidence ratios (SIRs) were calculated relative to a matched cohort from the general population using the Netherlands Cancer Registry. Results: A total of 2649 patients with CVT (median [IQR] age, 44.5 [30.7-56.4] years; 1856 [70.1%] female) were included. Cancer was diagnosed in 119 patients during a median (IQR) follow-up of 4.7 (1.9-8.9) years, of whom 29 (24.4%) had hematologic cancer. The cumulative incidence of cancer was 5.9% (95% CI, 4.8%-7.2%) after 10 years and was highest in men aged 50 years or older (13.5%; 95% CI, 9.1%-18.7%). Patients with CVT had an increased rate of cancer compared with the reference cohort during the entire follow-up, but the difference narrowed over time (SIRs of 3.35 [95% CI, 2.41-4.55] and 1.40 [95% CI, 1.14-1.69] at 1 and 10 years, respectively). The rate was increased both in patients younger than 50 years (SIRs of 6.70 [95% CI, 3.97-10.59] and 1.72 [95% CI, 1.24-2.34] at 1 and 10 years, respectively) and those 50 years or older (SIRs of 2.41 [95% CI, 1.53-3.62] and 1.25 [95% CI, 0.96-1.60] at 1 and 10 years, respectively), as well as in male patients (SIRs of 3.59 [95% CI, 2.16-5.61] and 1.69 [95% CI, 1.25-2.23] at 1 and 10 years, respectively) and female patients (SIRs, 3.17 [95% CI, 1.99-4.80] and 1.22 [95% CI, 0.92-1.58] at 1 and 10 years, respectively). Conclusions and Relevance: This cohort study of patients with CVT found an increased risk of cancer during follow-up regardless of age or sex. Men 50 years or older had the highest absolute risk, whereas younger patients had the highest relative risk. Physicians should be vigilant for signs of cancer after CVT, and further research on screening for cancer after CVT is warranted.