Unprovoked venous thromboembolism and subsequent cancer risk: a population-based cohort study

Abstract

ESSENTIALS: A relationship between unprovoked venous thromboembolism (VTE) and cancer risk was investigated. We collected 27,751 VTE patients and compared them with 110,409 frequency-matched people without VTE. This cohort study showed significantly higher risks of overall and site-specific cancers in the VTE group. There is an increased risk in the first 6 months after VTE, and VTE can be an indicator of occult cancer.

Background: We investigated the relationship between unprovoked venous thromboembolism (VTE) and subsequent cancer risk in Taiwan, focusing on both short-term and long-term cancer development.

Methods: For the case group, we obtained data on 27,751 patients diagnosed with unprovoked VTE between 1 January 1998, and 31 December 2008. For the comparison group, four people without unprovoked VTE were frequency-matched with each unprovoked VTE patient according to age, sex, and index year. Cox proportional hazards regression models were employed to determine the effects of unprovoked VTE on cancer risk.

Results: Overall cancer risk was significantly higher in the unprovoked VTE group than in the comparison group (adjusted hazard ratio = 2.26, 95% confidence interval = 2.16-2.37). The increased risk was observed in both men and women in various age groups. The patients in the unprovoked VTE group showed a significantly increased risk of cancer at all site-specific cancer sites. Analyses stratified according to follow-up duration revealed that significant differences were more evident between the two groups over a follow-up duration of < 0.5 years than over a follow-up duration of ≥ 3 years. Furthermore, the 1-year mortality risk of cancer patients with unprovoked VTE was significantly higher than that for cancer patients in the non-VTE group.

Conclusion: The results of this study show that unprovoked VTE is associated with a consistently high risk of subsequent cancer diagnosis. This is particularly true in the first 6 months after VTE. It suggests that unprovoked VTE can be an indicator of occult malignancy.

Keywords: ICD-9; cohort study; neoplasms; risk; venous thromboembolism.