Association between cancer types, cancer treatments, and venous thromboembolism in medical oncology patients.

Nearly 20% of all venous thromboembolism (VTE) occurs in cancer patients, and as many as 78% of cancer patients who develop a thrombotic event do so as outpatients. The risk of VTE in cancer patients is influenced by the type of cancer, its stage and histology, the presence of thrombophilia, and the many therapeutic interventions they receive (eg, surgery, chemotherapy, radiotherapy, supportive care). The greatest VTE risk appears to occur early after cancer diagnosis and in patients with late- or metastatic-stage malignancy. VTE most often occurs in cancers of the pancreas, ovary, kidney, lung, stomach, and brain, as well as in hematologic malignancies such as lymphoma and myeloma. The clinical consequences of thrombosis in cancer patients are typically more severe and more costly than events in patients without cancer. Patient-, cancer-, and treatment-related factors should be considered when assessing individual patients for their risk of VTE. Primary pharmacologic VTE prophylaxis should be given to all hospitalized medical and surgical oncology patients at risk, and this therapy should be considered for high-risk ambulatory outpatients (eg, myeloma patients receiving highly thrombogenic chemotherapeutic regimens, very-high-risk solid tumor patients with Khorana scores ≥3) who have no contraindications to anticoagulants.