Risk and Prognosis of Cancer in Patients With Cerebral Venous Thrombosis Compared With the Danish General Population.

Background: Whether cerebral venous thrombosis (CVT) is a marker of cancer in clinical practice remains unknown. Little is known about the prognosis of cancer detected subsequent to CVT.

Methods: We used Danish nationwide registries (1996-2019) to identify patients with a first-time primary inpatient diagnosis of CVT without a history of cancer (N=811, 65% women, median age 42 years). We assessed the risk of an incident cancer diagnosis using standardized incidence ratios (SIRs). This measure contrasts the number of observed cancers among patients with CVT to the number of expected cancers where patients with CVT have the same cancer risk as the general population. We used Kaplan-Meier survival analysis and Cox regression to compare the survival of patients with both cancer and CVT with the survival of patients with cancer but without CVT, matched on cancer site, sex, age, and year of cancer diagnosis.

Results: Observing 43 incident cancer cases during follow-up, the overall SIR was unity (SIR, 1.04 [95% CI, 0.75-1.40]). However, the risk was ≈7-fold the expected level in the first 3 months following CVT diagnosis (SIR, 7.00 [95% CI, 3.02-13.80]) and ≈2-fold the expected level from 3 to 12 months following CVT diagnosis (SIR, 2.21 [95% CI, 0.89-4.56]). By 12 months following CVT diagnosis, the risk resembled the expected level (SIR, 0.76 [95% CI, 0.50-1.09]). Survival among cancer patients with prior CVT versus cancer patients without prior CVT was 91% versus 87% after 6 months and 65% versus 70% after 5 years. The adjusted hazard ratio of death was 0.78 (95% CI, 0.44-1.38).

Conclusions: Patients with CVT were not at overall increased risk of a cancer diagnosis, except in the first 3 months after diagnosis during which period the risk was elevated ≈7-fold. The estimate from this early period, however, was based on only a few cancer diagnoses. Unlike other forms of venous thrombosis, a prior diagnosis of CVT did not negatively impact cancer survival.