Risk factors for incident venous thromboembolism in active cancer patients: A population based case–control study

• We tested cancer and non-cancer characteristics as predictors of cancer-associated VTE.
• Cancer site, stage, liver metastasis, chemotherapy, and progestin increased VTE risk.
• BMI, hospitalization, central venous catheter and infection increased VTE risk.
• These characteristics can be used to identify high VTE-risk active cancer patients.

BackgroundIndependent risk factors for cancer-associated incident venous thromboembolism (VTE) and their magnitude of risk are not fully characterized.AimTo identify non-cancer and cancer-specific risk factors for cancer-associated incident VTE.MethodsIn a population-based retrospective case–control study, we used Rochester Epidemiology Project and Mayo Clinic Cancer Registry resources to identify all Olmsted County, MN residents with active cancer-associated incident VTE, 1973–2000 (cases; n = 570) and 1–3 residents with active cancer matched to each case on age, sex, date and duration of active cancer (controls; n = 604). Using conditional logistic regression, we tested cancer and non-cancer characteristics for an association with VTE, including a cancer site VTE risk score.ResultsIn the multivariable model, higher cancer site VTE risk score (OR = 1.4 per 2-fold increase), cancer stage ≥ 2 (OR = 2.2), liver metastasis (OR = 2.7), chemotherapy (OR = 1.8) and progesterone use (OR = 2.1) were independently associated with VTE, as were BMI < 18.5 kg/m2 (OR = 1.9) or ≥ 35 kg/m2 (OR = 4.0), hospitalization (OR = 7.9), nursing home confinement (OR = 4.7), central venous (CV) catheter (OR = 8.5) and any recent infection (OR = 1.7). In a subgroup analysis, platelet count ≥ 350 × 109/L at time of cancer diagnosis was marginally associated with VTE (OR = 2.3, p = 0.07).ConclusionCancer site, cancer stage ≥ 2, liver metastasis, chemotherapy, progesterone, being underweight or obese, hospitalization/nursing home confinement, CV catheter, and infection are independent risk factors for incident VTE in active cancer patients.