BackgroundThe Cancer-VTE Registry was a large-scale, multicenter, prospective registry designed to investigate real-world data on venous thromboembolism (VTE) incidence and risk factors in adult Japanese patients with solid tumors. This pre-specified subgroup analysis aimed to estimate the incidence of VTE, including VTE types other than symptomatic VTE, and identify risk factors of VTE in stomach cancer from the Cancer-VTE Registry.MethodsStage II–IV stomach cancer patients who planned to initiate cancer therapy and underwent VTE screening within 2 months before registration were enrolled.ResultsOf 1,896 patients enrolled, 131 (6.9%) had VTE at baseline, but 96.2% were asymptomatic. Female sex, age ≥ 65 years, VTE history, and D-dimer > 1.2 μg/mL were independent risk factors of VTE at baseline. Notably, patients with D-dimer > 1.2 µg/mL at the time of cancer diagnosis had an approximately 20-fold risk of VTE. During follow-up, event incidences were symptomatic VTE, 0.3%; incidental VTE requiring treatment, 1.1%; composite VTE, 1.4%; bleeding, 1.6%; cerebral infarction/transient ischemic attack/systemic embolic events, 0.7%; and all-cause death, 15.0%. The incidence of all-cause death was higher in patients with VTE vs without VTE at baseline (adjusted hazard ratio 1.67; 95% confidence interval 1.21–2.32; p = 0.002).ConclusionsVTE prevalence at the time of cancer diagnosis was not negligible and was extremely high when the patients had high D-dimer. VTE screening by D-dimer before starting cancer treatment is advisable, even for asymptomatic patients, regardless of whether the patient is undergoing surgery or chemotherapy.Trial registrationUMIN000024942.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10120-023-01378-1.