Among patients with a first episode of unprovoked venous thromboembolism (VTE), the contemporary one-year risk of detecting occult cancer is approximately 4% to 7%. Of these cases, 30% to 60% are missed by routine limited screening for cancer. RNA profiling of platelets is a promising, highly accurate biomarker for cancer detection, but its clinical utility in patients with unprovoked VTE is unknown. The objective of the present study is to evaluate the diagnostic accuracy of platelet RNA profiling in detecting occult cancer in patients with unprovoked venous thromboembolism. Secondary objectives include evaluation of other biomarkers for cancer, prediction of bleeding, and prediction of recurrent VTE.

Inclusion Criteria:

• First episode of objectively confirmed, symptomatic, unprovoked symptomatic pulmonary embolism and/or distal or proximal deep vein thrombosis of the leg
• Age 40 years or older
• Written informed consent

Exclusion Criteria:

• known malignant disease prior to VTE defined as a cancer diagnosis or cancer treatment within the past 5 years (of note: suspected but unconfirmed cancer at diagnosis of VTE is allowed);
• trauma or fracture of the leg, surgical procedures, general anesthesia, or immobilization greater than 3 days within previous 3 months;
• previous unprovoked venous thromboembolism;
• known hereditary or acquired thrombophilia;
• current pregnancy or puerperium (up to 3 months postpartum);
• current estrogen therapy.
• Greater than 10 days after VTE diagnosis;
• Inability for blood withdrawal at baseline;
• Inability or refusal to provide written informed consent.

Consecutive patients of 40 years or older with a first episode of objectively confirmed, symptomatic unprovoked distal or proximal deep vein thrombosis or pulmonary embolism.