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Extensive cancer screening may not benefit patients with unprovoked venous thromboembolism
Extensive cancer screening for individuals who experience unprovoked venous thromboembolism initially may detect more cancer cases than a limited occult screening approach.
However, the difference in proportion of early-stage cancers detected by each approach did not reach statistical significance, according to results of a systematic review and meta-analysis published in Annals of Internal Medicine. Whether the more extensive screening strategy improves patient outcomes also remains unclear, researchers wrote.
“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 VTE,” Nick van Es, MD, of the department of vascular medicine at Academic Medical Center in Amsterdam, and colleagues wrote.
Unprovoked VTE may be the initial sign of occult cancer, so clinicians often consider cancer screening for these patients. However, the extent to which this screening should be performed has been controversial due to the potential for false-positive results and the need for additional tests that increase health care costs and subject patients to procedure-related complications, according to study background.
Researchers used the Medline and Embase databases, as well as the Cochrane Central Register of Controlled Trials, to identify prospective studies that evaluated cancer screening strategies for adults with unprovoked VTE. All studies began enrolling patients after Jan. 1, 2000, and included at least 12 months of follow-up.
Two investigators independently reviewed abstracts and full-text articles to assess the potential for bias.
The final analysis included 10 studies that contained individual data for 2,316 patients (mean age, 60 years; 61% men). Seven studies enrolled patients prior to any screening procedures; of those, three directly compared extensive screening and limited screening, and the other four only evaluated extensive screening.
Forty-seven percent of patients experienced pulmonary embolism with or without deep vein thrombosis; 49% experienced proximal leg DVT; and 2.2% experienced distal leg DVT. The remainder of patients experienced other types of index VTE.
Most patients (58%) underwent extensive cancer screening, which — although heterogenous across studies — often included imaging with CT and ultrasonography of the abdomen or whole-body PET/CT. The remainder underwent limited screening, which included a combination of medical history taking, physical exam, chest radiography, age- and sex-specific tests (eg, PSA test or mammography), and basic blood tests.
Median follow-up ranged from 1 year to 2.5 years (overall median, 500 days).
Overall cancer prevalence within the 12 months following VTE diagnosis was 5.2% (95% CI, 4.1-6.5).
Occult cancer was detected at screening in a higher percentage of patients who underwent extensive screening (4.5%; 95% CI, 3.4-5.9) than limited screening (2.4%; 95% CI, 1.6-3.6) who underwent limited screening.
Results of the three studies that directly compared extensive screening with limited screening strategies showed a higher initial prevalence among those who underwent extensive screening (OR = 2; 95% CI, 1.2-3.4), but the difference was smaller at 12 months (OR = 1.4; 95% CI, 0.89-2.1).
However, results showed no statistically significant difference between the proportion of early-stage solid cancers detected by extensive screening or limited screening.
van Es and colleagues determined cancer prevalence increased linearly with age, with patients aged 50 years or older demonstrating a sevenfold higher prevalence than younger patients (OR = 7.1; 95% CI, 3.1-16).
Researchers acknowledged several possible limitations, including differences in patient characteristics, variations in extensive screening strategies and the lack of long-term mortality data.
“This review shows that, although an extensive screening strategy may initially detect more cancer than a limited one, whether that translates to improved outcomes is unclear,” Geno Merli, MD, co-director of Jefferson Vascular Center at Thomas Jefferson University Hospital, and Howard Weitz, MD, director of the division of cardiology at Thomas Jefferson University Hospital, wrote in an accompanying editorial.
“It supports the opinion that, for most patients, history, physical examination, basic laboratory studies, and age-, sex- and risk factor-specific tests comprise the initial cancer screening after the diagnosis of unprovoked VTE,” Merli and Weitz added. “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.” – by Mark Leiser
Disclosures: van Es reports no relevant financial disclosures. Please see the full study for a list of all researchers’ relevant financial disclosures. Merli and Weitz report no relevant financial disclosures.