Risk of site-specific cancer in incident venous thromboembolism: A population-based study

Background The risk of venous thromboembolism (VTE) by cancer site is uncertain. Objective To estimate VTE risk by tumor site. Methods We enumerated observed active cancers by cancer site for Olmsted County, MN residents with incident VTE over the 13-year period, 1988-2000 (n = 345 of 1417). We used 1988-2000 Iowa State Surveillance, Epidemiology, and End Results (SEER) data to estimate the expected age-specific prevalence of cancer by cancer site for all VTE cases; standardized Morbidity Ratios (SMR) for each cancer site were estimated by dividing the observed number of cancers in the VTE incident cohort by the expected number. Relative risk regression was used to model the observed number of cancers of each site, adjusting for the expected value based on SEER prevalence data, using generalized linear regression with a Poisson error and the natural log of the age- and sex-group expected count as an offset. Results For men and women with VTE, all cancer sites had an increased SMR, ranging from 4.1 for head neck cancer to 47.3 for brain cancer. Among women, the SMR for breast, ovarian and other gynecologic cancers were 8.4, 13.0 and 8.4, respectively; for men, prostate cancer SMR was 7.9. Adjusting for age and sex, the relative risk (RR) of cancer in VTE cases was associated with cancer site in a multivariable model (p < 0.001). Adjusting for age and sex, pancreatic, brain, other digestive cancers, and lymphoma had significantly higher RRs than the grouped comparison cancers. Conclusions Incident VTE risk can be stratified by cancer site.