Cancer-Associated Venous Thromboembolic Disease

Dr. Michael Streif of Johns Hopkins reviews cancer-associated venous thromboembolism: epidemiology, risk factors, prevention, DOAC use, and treatment.

Key Takeaways

VTE is a major and frequently underrecognized complication in patients with cancer, with substantially worse outcomes than in the general population.
Clot risk varies with cancer type, stage, treatment, and patient-level factors, so risk assessment should be individualized.
Anticoagulant dosing, especially for DOACs, should consider body weight and, where relevant, drug-level monitoring.
Bleeding risk is highest early in therapy, which should inform monitoring and anticoagulation decisions.
Recurrent VTE despite anticoagulation warrants evaluation for adherence, drug absorption, and other causes such as antiphospholipid syndrome.

What the video covers

Dr. Michael Streif (Johns Hopkins) presents an NCCN continuing-education talk on cancer-associated venous thromboembolism (VTE).
Clots are common: roughly 900,000 DVT/PE events per year in the US, with 50,000-100,000 fatal PEs, making VTE the third leading cause of cardiovascular death.
Patients with cancer have about ninefold higher VTE rates than those without cancer, based on a Danish national registry study (Mulder et al., 2021).
Clotting risk begins rising in the months before a cancer diagnosis, peaks around the first six months of treatment, falls in remission, and rises again at relapse.
Cancer outcomes are worse after VTE: threefold higher recurrence, twofold higher fatal PE, twofold higher fatal bleeding, and fivefold higher mortality.
Risk factors include age, race/ethnicity (African Americans slightly higher, Asians lower), genetic mutations such as factor V Leiden and prothrombin, cancer type, histology, stage, and treatment timing.
Newer targeted therapies carry clot risk comparable to chemotherapy, contrary to early expectations.
Prophylaxis and anticoagulant dosing should account for body weight, since drug distribution depends on blood volume.
Risk-scoring tools such as the Khorana score are discussed, including a more refined model validated at Baylor and in a large national trial.
Treatment decisions depend on clot location and severity (e.g., proximal, above-knee, or upper-extremity DVT) and clinical status such as hypotension or hypoxia.

Chapters

How much more likely are patients with cancer to develop a blood clot?

According to a Danish national registry study cited in the talk (Mulder et al., 2021), patients with cancer have roughly ninefold higher rates of venous thromboembolism than patients without cancer. The risk rises even before the cancer is diagnosed and peaks in the first months of treatment.

What outcomes are worse for cancer patients who develop a clot?

The speaker notes that patients with cancer and VTE are about threefold more likely to have a recurrent clot, twofold more likely to have a fatal PE, twofold more likely to have fatal bleeding, and fivefold more likely to die. These figures highlight the importance of careful management.

Do newer targeted cancer therapies cause fewer clots than chemotherapy?

No. The speaker explains that targeted therapies were initially expected to carry lower clot risk, but data show they are about as likely as chemotherapy to cause thrombosis.