Occult cancer in patients with unprovoked venous thromboembolism: Rationale, design, and methods of the VaLRIETEs study and the SOME-RIETE trial

Background Unprovoked venous thromboembolism (VTE) is considered when no clear major provoking factor for VTE is identified. Although the 1-year risk of diagnosing new cancer in these patients can be as high as 5%, the benefits of extensive screening remain uncertain. It is possible that in a risk-enriched population of patients, screening yields benefit. Recently, the RIETE score, a composite score including sex, age, chronic pulmonary disease, anemia, platelet count and previous VTE, was found to improve risk prediction for identification of occult cancer in patients with unprovoked VTE. As for screening tests, whole body 18F-fluorodeoxyglucose Positron Emission/Computed Tomography (18F-FDG PET/CT) is a promising and sensitive tool for occult cancer screening. Methods This manuscript summarizes the rationale and design of 2 prospective studies in patients with unprovoked symptomatic VTE: (1) ValRIETE is an international, multicenter, prospective, adaptative, cohort study that plans to include 1,550 patients; the adaptive design permits a sample size increase depending on the results of the predefined interim analysis. This study will enable the external validation of the RIETE score, with several ancillary aims related to additional clinical and biomarker predictors. Recruitment began in December 2022. (2) SOME-RIETE is an open-label, randomized, multicenter clinical trial that plans to enroll 650 patients with a RIETE score >= 3 to compare limited screening with limited screening plus whole body 18F-FDG PET/CT. The primary outcome is cancer diagnosis within 3 months after VTE event. Secondary outcomes include cancer diagnosis and mortality at 12 months. Conclusions This study provides clinically meaningful data on and the utility of extended screening of cancer by 18F-FDG PET/CT. Study Registration VaLRIETE study: ethics committee of the Virgen del Rocio University Hospital, Sevilla (Spain). https://www.juntadeandalucia.es/salud/portaldeetica/xhtml/inicio/inicio.iface (1687-N-22). Trial Registration SOME-RIETE: ClinicalTrials.gov (NCT03937583).