VENOUS THROMBOEMBOLISM AND CANCER

Background Although cancer has been clearly associated with venous thr omboembolism (VTE), many aspects of this relation are poorly understoo d, including the cancer sites most affected and the cancer risk during long-term follow-up. To clarify these relations, we carried out a lar ge, population-based analysis of VTE and cancer risk. Methods Using th e Swedish Inpatient Register and linkage to the nationwide Cancer Regi stry, we assessed cancer incidence during 1989 among 61 998 patients w ithout a previous cancer diagnosis admitted to hospital between 1965 a nd 1983 for VTE. To measure possible increases in cancer risk, we comp uted standardised incidence ratios (SIRs) using Swedish national cance r rates for the period of the study. Findings At the time of thromboem bolic admission or during the first year of follow-up, 2509 cancers we re diagnosed (SIR 3.2, 95% CI 3.1-3.4). The SIR for polycythaemia vera was 12.9 (8.6-18.7), and the SIRs for cancers of the liver, pancreas, ovary, and brain, and for Hodgkin lymphoma also exceeded 5.0. Patient s aged less than 65 years had higher SIRs than those who were older. I n subsequent years, 6081 cancers were diagnosed (1.3, 1.3-1.3). Even 1 0 years or more after admission to hospital with VTE, cancer incidence had increased (1.3, 1.3-1.4). Interpretation At the time of VTE or in the first year afterwards, we found a large increase in the risk for diagnosis of virtually all cancers. In subsequent years, a persistent 30% increase in risk remains. Either premalignant change promotes thro mbosis, or cancer and thrombosis share common risk factors.