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Routine CT does not improve occult cancer detection after unprovoked VTE
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A low prevalence of occult cancer occurred among patients with a first unprovoked venous thromboembolism, according to the results of a randomized, controlled trial.
Further, routine, comprehensive CT screening of the abdomen and pelvis did not detect significantly more occult cancers compared with a limited screening strategy, results also showed.
VTE may be one of the earliest signs of cancer, according to study background. However, there is currently no standard practice regarding screening for occult cancer in individuals with unprovoked VTE.
Marc Carrier, MD, associate professor of medicine at the University of Ottawa and senior scientist in the clinical epidemiology program at the Ottawa Hospital Research Institute, and colleagues conducted the open-label, randomized, controlled Screening for Occult Malignancy in Patients with Idiopathic VTE (SOME) trial to assess the efficacy of using pelvic and abdominal CT as a screening mechanism for occult cancer among patients with a first unprovoked VTE.
The analysis included 854 patients (mean age, 54 years). The researchers randomly assigned patients to receive limited occult cancer screening — composed of basic blood testing; chest radiography; and screening for breast, cervical and prostate cancers — alone (n = 421) or with comprehensive CT of the abdomen and pelvis (n = 423).
Confirmed cancer diagnosis missed by the screening strategy and detected by the end of a 1-year follow-up period served as the primary endpoint.
Among the entire patient population, 3.9% (n = 33) of the patients with VTE received a new diagnosis of occult cancer between randomization and follow-up. Fourteen cancers occurred in the screening-only arm, whereas nineteen cancers occurred in the screening plus CT arm.
The limited screening strategy missed four cancers, whereas the limited screening plus comprehensive CT strategy missed five cancers.
In the secondary outcomes analyses, the researchers did not observe a significant difference between the limited screening alone vs. limited screening plus CT arms with regard to the mean time to a cancer diagnosis (4.2 months vs. 4 months), VTE recurrence (3.3% vs. 3.4%) or cancer-specific mortality (1.4% vs. 0.9%).
Neither treatment protocol produced an association with reported serious adverse events.
The researchers acknowledged the use of an open-label trial protocol — which increases the risk for bias compared with placebo-controlled trials — as a study limitation.
“The rate of detection of occult cancer in our study was lower than expected,” Carrier and colleagues concluded. “A systematic review and meta-analysis of the literature that pooled data from older clinical studies showed a rate of occult cancer detection of up to 10% at 12 months after a diagnosis of unprovoked VTE. … However, it is unlikely that the screening methods would have produced significantly different results even if the incidence of cancer has been higher.” – by Cameron Kelsall
Disclosure: Please see the full study for a list of the researchers’ relevant financial disclosures.
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