Outcomes of limited cancer screening after unprovoked VTE similar to extensive screening
The overall prevalence of cancer in the 12 months after a diagnosis of venous thromboembolism was 5.2%. While the point prevalence was higher in patients receiving extensive screening than in those receiving limited screening, there was no significant difference at one year.
Extensive cancer screening after an unprovoked venous thromboembolism (VTE) identified more cancers than limited screening, but at uncertain benefit to patients, a review found.
The systematic review and meta-analysis included 10 prospective studies that evaluated cancer screening strategies in adults with unprovoked VTE, were conducted in 2000 or since, and had at least 12 months of follow-up. A total of 2,316 patients were included and they had a mean age of 60 years. More than half of the patients (58%) received extensive screening, which included tests such as CT, ultrasonography, or whole-body positron emission tomography-CT. The rest received limited screening, which was defined as the combination of history taking, physical exam, basic blood tests (complete blood count and creatinine and liver function tests), chest X-ray, and age- and sex-specific tests, such as mammography or prostate-specific antigen testing.
The overall prevalence of cancer in the 12 months after VTE diagnosis was 5.2% (95% CI, 4.1% to 6.5%). Initially, the point prevalence was higher in patients receiving extensive screening than in those receiving limited screening (odds ratio [OR], 2.0; 95% CI, 1.2 to 3.4), but there was no significant difference at one year (OR, 1.4; 95% CI, 0.89 to 2.1). Overall, cancer prevalence increased with linearly with patients' age; the OR for patients 50 years or older compared to those younger than 50 years was 7.1 (95% CI, 3.1 to 16). Results were published online by Annals of Internal Medicine on Aug. 22.
The results show that cancer is detected in 1 in 20 patients within a year of unprovoked VTE, the study authors concluded. They noted that about two-thirds of the cancer cases were detected by screening. The prevalence of cancer observed in this study is about half that found in a previous systematic review of the topic, said the authors, who expressed confidence that the current findings likely represent current practice and so can be used to inform patients and assess the risks and benefits of screening.
The review also showed that the probability of cancer is low in young patients and women receiving estrogen. “These considerations raise the question of whether screening for occult cancer should be offered to low-risk patients,” the authors said. Another clinically applicable finding was that the period prevalence of cancer in the second year after VTE was about 1%. “Hence, continued routine surveillance and increased awareness for cancer beyond the first year may not be indicated,” the authors said. In the first year after VTE, a thorough medical history and physical exam “are probably the most important screening components,” with complete blood counts and liver function tests also showing effectiveness, the authors said.
An accompanying editorial reviewed the history of research on the association between VTE and cancer in addition to the findings of the current analysis. “We believe that extensive screening is not cost-effective and that further study is needed to better define the effect of advanced imaging in patients older than 50 years,” the editorialists wrote.