Questions under study: The association of deep vein thrombosis (DVT) and cancer is well established. It is controversial how large the association is and how extensive the evaluation for an underlying cancer should be.
Principles and methods: 485 patients without a known cancer and a proven DVT formed the cohort of a retrospective study. Newly diagnosed (prevalent) cancers in patients with idiopathic (IDVT) and secondary (SDVT) during the index hospitalisation were compared and the contribution of the steps in an institutional tumour search program was analysed. The incidence of cancer in 204 patients with IDVT and 230 patients with SDVT during follow-up was determined.
Results: During the index hospitalisation routine evaluation revealed eleven cancers in 236 patients (4.7% [95%-CI: 2.0-7.3]) with IDVT and five cancers in 249 patients (2.0% [95%-CI: 0.3-3.7]) with SDVT. Combining patient history, clinical examination, routine laboratory tests and chest x-ray showed a sensitivity of 88% and a specificity of 79% for the diagnosis of cancer. Abdominal ultrasound did not significantly increase the yield. 93% of the patients were followed for up to 5 years (mean 32 months). Sixteen cancers occurred in 204 patients (7.8% [95%-CI: 4.0-11.5]) with IDVT and ten in 230 patients (4.35% [95%-CI: 1.7-7.0]) with SVDT (p<0.001).
Conclusion: Prevalence and incidence of cancer were higher in IDVT patients compared to those with SDVT. Combining patient history, clinical examination, simple laboratory tests, and a routine chest x-ray is an appropriate strategy to detect underlying cancer in patients with IDVT. Routine abdominal ultrasound can safely be omitted.