The SOME trial: Screening for occult malignancy in unprovoked venous thromboembolism [Classics Series]

1. Patients with a first unprovoked venous thromboembolism were randomized to either limited-screening for occult malignancy or limited-screening plus computed tomography (CT) of the abdomen and pelvis.

2. There were no significant differences between the two strategies in the number of occult malignancies diagnosed, and the number of occult malignancies missed by the initial screen.

Original Date of Publication: August 2015

Study Rundown: Venous thromboembolism is a common class of disease characterized by the formation of clots in the deep veins. These clots can be classified as being provoked, or unprovoked in the absence of a known risk factor (i.e., overt active cancer, current pregnancy, thrombophilia, previous clot, recent immobilization, recent major surgery). Unprovoked venous thromboembolism has been thought to be an early sign of cancer, as previous studies had demonstrated that up 10% of patients were diagnosed with malignancy in the year afterwards. Thus, an area of uncertainty for clinicians was how aggressively patients with unprovoked venous thromboembolism should be investigated for occult malignancy. The Screening for Occult Malignancy in Patients with Idiopathic Venous Thromboembolism (SOME) trial sought to address this question.

In summary, the trial randomized individuals with unprovoked venous thromboembolism to either limited-screening for occult malignancy or to limited-screening plus comprehensive CT of the abdomen and pelvis. There were no significant differences between the two groups in the number of occult malignancies identified. There were also no significant differences between the two strategies in the number of malignancies initially missed on screening, but subsequently discovered. Based on these findings, a strategy of conducting limited-screening for occult malignancy may be appropriate for individuals who present with a first unprovoked venous thromboembolism.

Click to read the study in NEJM

In-Depth [randomized controlled trial]: A total of 854 patients from 9 participating Canadian centers were included in the intention-to-test analysis. Patients were eligible if they had a new diagnosis of first unprovoked symptomatic venous thromboembolism (i.e., proximal lower extremity deep-vein thrombosis, pulmonary embolism, or both). Exclusion criteria included age <18 years, refusal or inability to provide informed consent, allergy to contrast media, creatinine clearance <60 mL/minute, weight >130 kg, ulcerative colitis, and glaucoma. Included patients were randomized in a 1:1 fashion to receive either limited occult-cancer screening (i.e., basic bloodwork, chest radiography, and recommended sex-specific screening) or limited occult-cancer screening plus comprehensive CT scan of the abdomen and pelvis. The primary outcome was newly diagnosed cancer during the 1-year follow-up period in patients with negative screen for occult malignancy. Secondary outcomes were the number of occult malignancies diagnosed, the number of early cancers diagnosed in screening and during follow-up, the incidence of recurrent venous thromboembolism, 1-year cancer-related mortality, and 1-year overall mortality.

There were no significant differences between the two groups in the number of occult cancers diagnosed. A total of 14 patients (3.2%; 95%CI 1.9 to 5.4%) in the limited-screening group and 19 patients (4.5%; 95%CI 2.9 to 6.9%) in the limited-screening plus CT group received diagnoses of occult cancers (p = 0.28). In both groups, several occult malignancies were missed by the initial screening strategies, with 4 (29%; 95%CI 8 to 58%) missed in the limited-screening group and 5 (26%; 95%CI 9 to 51%) missed in the limited-screening plus CT group (p = 1.0). Kaplan-Meier analysis showed that there was no significant difference in time to detection of missed occult cancers between the two groups (p = 0.87). There were no significant differences between the groups in the incidence of recurrent venous thromboembolism (p = 1.0), cancer-related mortality (p = 0.75), or overall mortality (p = 1.0).

Image: PD

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