Screening for Occult Cancer in Patients With Unprovoked Venous Thromboembolism


Key Points

  • Occult cancer is detected in 1 in 20 patients within 12 months of receiving a diagnosis of unprovoked venous thromboembolism. Older age is associated with a higher cancer prevalence.
  • An extensive screening strategy was associated with a twofold higher probability of cancer detection at initial screening.
  • Although an extensive screening strategy may initially detect more cancer cases than limited screening, whether this translates into improved patient outcomes remains unclear. 

Because unprovoked venous thromboembolism may be the first sign of occult cancer, or cancer of an unknown primary origin, screening is often considered in patients with the condition to detect underlying cancer at an early, curable stage. However, extensive screening tests may yield false-positive findings, requiring additional testing and the potential of exposing patients to procedure-related complications and anxiety.

To help clinicians tailor screening decisions, van Es et al performed a systematic review and meta-analysis of individual patient data to estimate the prevalence of occult cancer in patients with unprovoked venous thromboembolism. The study found that occult cancer is detected in 1 in 20 patients within a year of receiving a diagnosis of unprovoked venous thromboembolism and that older age is associated with a higher cancer prevalence. Although extensive screening detected twice as many cancer cases as limited screening alone, no statistically significant difference was found in cancer detection between the two approaches. The study was published in the Annals of Internal Medicine.

Study Methodology

The researchers analyzed patient data obtained from MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases from November 2007 to January 2016. Ten eligible studies were identified, and data were obtained from 2,316 patients, with a mean age of 60 years. Fifty-eight percent of the patients received extensive screening. To be eligible, studies must have prospectively included consecutive adult patients with unprovoked, confirmed deep venous thrombosis or pulmonary embolism and followed them for a minimum of 12 months for potential cancer.

Study Findings

The researchers found that the 12-month period prevalence of cancer after venous thromboembolism diagnosis was 5.2% (95% confidence interval [CI] = 4.1%–6.5%). The point prevalence of cancer was higher in patients who had extensive screening than in those who had more limited screening initially (odds ratio [OR] = 2.0; 95% CI = 1.2–3.4) but not at 12 months (OR = 1.4; 95% CI = 0.89–2.1). Cancer prevalence increased linearly with age and was sevenfold higher in patients aged 50 years or older than in younger patients (OR = 7.1; 95% CI = 3.1–16).

“An extensive screening strategy was associated with a 2-fold higher probability of cancer detection at initial screening, at the obvious expense of an increase in the number of targeted tests for cancer. Despite the substantial increase in cancer detection with extensive screening, not enough evidence exists yet to support the routine use of these tests in patients with unprovoked [venous thromboembolism].… Given the relatively short follow-up of the included studies, it remains unclear whether the increase in cancer detection by extensive screening tests will translate into benefits with regard to important patient outcomes, such as lower morbidity and mortality,” concluded the study authors.

Nick van Es, MD, of the Academic Medical Center in Amsterdam, The Netherlands, is the corresponding author of this study.


The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.