RESULTS
We identified 15,348 patients with deep venous thrombosis and 11,305 patients with pulmonary embolism, each cohort consisting of approximately similar proportions of men and women. In the two cohorts combined, 33 percent were below the age of 60 years at the time of the thromboembolic episode, 37 percent were 60 to 74 years old, and 30 percent were 75 or older. On average, the patients with deep venous thrombosis were followed for longer periods than the patients with pulmonary embolism (6.1 vs. 3.6 years).
Standardized incidence ratios of 1.3 for all types of cancer were observed in both the cohort with deep venous thrombosis and the cohort with pulmonary embolism, based on 1737 observed and 1372 expected cases among the patients with deep venous thrombosis (95 percent confidence interval for the standardized incidence ratio, 1.21 to 1.33) and 730 observed and 556 expected cases among those with pulmonary embolism (95 percent confidence interval for the standardized incidence ratio, 1.22 to 1.41). There were no particular differences in risks between men and women.
The risk for both cohorts was three times the expected level during the first six months of follow-up, after which the risk declined to a constant level of slightly more than 1.0 one year after the thrombotic event and throughout the study period