Venous thromboembolism and radiation therapy: The final radiation‐induced thrombosis study analysis

BACKGROUND: Thromboembolic events frequently complicate the course of malignancy and represent a major cause of morbidity and mortality in cancer patients. In contrast to chemotherapy and other systemic therapies, little is known about the impact of ionizing radiations on the incidence of venous thromboembolism (VTE) in cancer patients. METHODS: In the present prospective study, we aimed to investigate the incidence, management, and outcome of VTE in newly diagnosed cancer patients who received curative radiotherapy. RESULTS: VTE was found in 8 patients, out of 401 patients at a median time of 80 days after radiotherapy initiation. The incidence rate of VTE at 6 months post‐treatment was 2% (95% CI, 0.9–3.7), with 50% of cases occurring during the radiotherapy course and 50% of cases in patients who received or were receiving chemotherapy. As none of the patients harbored a personal history of VTE, no prophylactic measure was initiated during cancer therapy. Most patients received monotherapy with low‐molecular‐weight heparin and were still on surveillance at the end of the study. No specific clinical risk factor was identified that might systematically indicate the need of thromboprophylaxis in the context of curative radiotherapy. CONCLUSIONS: Although this pan‐cancer descriptive study did not relate an increased risk of short‐term thrombosis following ionizing radiation, it provides important insight as a basis for future studies with subcategories of cancer, in order to in fine guide further recommendations in frail patients. CLINICAL TRIAL REGISTRATION NUMBER: NCT02696447.