Screening for Occult Cancer in Unprovoked Venous Thromboembolism
What is the efficacy of a screening strategy for occult cancer in patients with a first unprovoked venous thromboembolism (VTE)?
SOME (Screening for Occult Malignancy in Patients with Idiopathic Venous Thromboembolism) was a multicenter, open-label trial in which 854 patients with a first unprovoked VTE were randomized to limited occult-cancer screening (basic blood testing; chest radiography; screening for breast, cervical, and prostate cancer) or the limited occult-cancer screening regimen plus a computed tomography (CT) of the abdomen and pelvis. The primary outcome was confirmed cancer within the first year of follow-up that was missed by the screening strategy of either group.
Of the 854 patients with a first unprovoked VTE, 33 (3.9%) had a new diagnosis of occult cancer in the 1 year of follow-up. The limited occult-cancer screening group experienced 14 (3.2%) cancer diagnoses, while the group that included CT scanning experienced 19 (4.5%) cancer diagnoses (p = 0.28). The primary outcome of a missed cancer diagnosis based on screening strategy occurred in four patients (29%) from the limited occult-cancer screening group and five patients (26%) in the screening that included CT testing (p = 1.0). There was no difference in the mean time to a cancer diagnosis between the two study groups (4.2 months vs. 4.0 months for limited-screening and limited-screening plus CT, respectively; p = 0.88) or in cancer-related mortality (1.4% and 0.9%, respectively; p = 0.75).
The authors concluded that the prevalence of occult cancer was low among patients with a first unprovoked VTE. They also concluded that routine CT scanning of the abdomen and pelvis did not provide significant incremental clinical benefit over a limited occult-cancer screening protocol.
This study has two important and practical findings for patients and clinicians. First, the rate of occult cancer identified in patients with unprovoked VTE was low (3.9%) despite a thorough evaluation. Second, there appeared to be no benefit to CT scanning of the abdomen and pelvis in addition to standard laboratory testing, chest radiography, and routine cancer screening tests. Of interest, the authors also were unable to show an increase in the utilization of additional testing for potential cancer diagnoses in the CT scan group as compared to the limited occult-cancer screening group (14.9% vs. 14.4%, p = 0.85). Clinicians can be reassured that a thorough history, physical examination and routine blood testing, chest radiography, and cancer screening tests are sufficient for patients with a first unprovoked VTE.
Keywords: Antineoplastic Protocols, Early Detection of Cancer, Neoplasms, Prevalence, Prostatic Neoplasms, Primary Prevention, Radiography, Tomography, X-Ray Computed, Venous Thromboembolism
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