Risk Factors Predictive of Occult Cancer Detection in Patients with Unprovoked Venous Thromboembolism

Background: Venous thromboembolism (VTE) may be the earliest sign of cancer. Risk factors associated with the presence of an occult cancer in patients with a first acute unprovoked VTE are unknown. We sought to assess the risk factors predictive of occult cancer detection in patients with a first unprovoked symptomatic VTE.

Methods:Post-hoc, pre-defined analyses of the multicenter open-label randomized controlled trial - Screening for Occult Malignancy in Patients with Idiopathic Venous Thromboembolism (SOME) trial (Carrier M et al. N Engl J Med 2015). The trial compared comprehensive computed tomography (cCT) of the abdomen and pelvis in addition to limited occult-cancer screening (complete history and examination, basic laboratory testing, chest radiography, and breast, cervical and prostate cancer screening) with limited occult-cancer screening alone in patients with a first unprovoked episode of VTE. Cox proportional hazard models were used to analyze the effect of specific risk factors on the outcome of occult cancer within 12 months of a diagnosis of unprovoked VTE. Multivariable analysis was performed using Cox proportional hazard models that included all variables that achieved a p value of < 0.20 in univariate analyses.

Results: A total of 854 patients were randomized to limited occult cancer screening only, or limited occult cancer screening in combination with a cCT. The mean age was 54 years and 67.4% were males. A total of 33 (3.9%; 95% C.I. 2.8-5.4) patients received a new diagnosis of cancer at 12 months follow-up. Age ≥ 60 years, compared to age < 60 years, was a predictor of cancer with a corresponding hazard ratio (HR) of 2.90 (95% C.I. 1.44-5.83, p=0.003). A previous provoked VTE in patients was also associated with a higher risk of developing cancer (HR=3.57, 95% C.I. 1.38-9.25, p=0.009). Patients with an unprovoked deep vein thrombosis (DVT), compared to either those with a pulmonary embolism (PE) only or both DVT and PE, seemed more likely to have a diagnosis of cancer. However, this trend was not statistically significant. (Table 1) These results were confirmed on multivariable analysis. Patients exhibiting one of these characteristics had a three-fold higher risk of occult cancer compared with patients without these characteristics. (Table 1)

Conclusion: Age at unprovoked VTE diagnosis (≥ 60 years) and prior provoked VTE are predictors of occult cancer, and could potentially be used to identify a group of patients with unprovoked VTE at high risk of underlying cancer.