When venous thrombotic events occur in apparently healthy older people (age,
60), the cause can be previously unsuspected cancer. Tumor cells, even in small numbers, release many procoagulants, which results in superficial and deep venous thrombosis (DVT). However, is the incidence of occult malignancy in patients with venous thromboembolism (VTE) high enough to justify extensive searches for tumors in such patients? And, if a tumor is discovered and treated, is risk for recurrent venous thrombosis lower, and is overall survival lengthened? These questions are addressed in a recent observational study that was performed by investigators from several European hospitals (using the RIETE Registry).Patients with documented VTE were considered to have occult malignancies if cancer was discovered from 15 to 90 days after thromboses occurred. Of 14,623 VTE patients who were assessed through January 2007, 178 (1.2%) met this definition. The cancers that were found most often were lung (16%), prostate (13%), colorectal (11%), and hematologic (11%). In half the patients, tumors had metastasized by the time they were discovered. Compared with patients who did not have malignancies, patients with cancer had significantly higher rates of recurrent VTE, major bleeding, and death. Predictors of occult malignancy were older age (60–75; P=0.01), unprovoked VTE (P<0.001), bilateral DVT (P=0.006), and anemia (P=0.001). Other factors, such as proximal DVT, symptomatic pulmonary embolism, or D-dimer levels >1000 mg/mL, were not predictive.
Comment: The findings of this study are discouraging, because patients whose VTEs were associated with cancer had poor prognoses, and, in most, tumors already had spread by the time of presentation. Thus, in such patients, intensive searching for a malignancy is unlikely to improve outcomes. However, often both patients and their physicians seek explanations for why VTEs developed, and, here, the results do provide some helpful information. Older age, unprovoked VTE, bilateral DVT, and anemia suggest that further investigation into possible malignant causes is needed. This should include thorough clinical history, physical examination, basic laboratory tests, and chest radiograph; if all these are negative, no additional evaluation is required. Suppose such investigation does reveal a tumor? Then, in addition to therapy for the cancer, long-term treatment with a low-molecular-weight heparin is preferable to warfarin therapy, which is associated with higher rates of thrombosis recurrence and anticoagulant-associated bleeding.
— David Green, MD, PhD
Published in Journal Watch Oncology and Hematology February 12, 2008
Citation(s):
Trujillo-Santos J et al. Clinical outcome in patients with venous thromboembolism and hidden cancer: Findings from the RIETE Registry. J Thromb Haemost 2008 Feb; 6:251.
Medline abstract (Free)