{"entity":{"id":"idea-upgrade-clot-risk-score-and-preventive-anticoagulation","kind":"idea","name":"A blood clot risk score at the start of chemotherapy, with preventive anticoagulation offered to those at higher risk","aka":[],"tldr":"People with cancer get blood clots more often than others. A score built from the cancer type and routine blood tests picks out those at higher risk, and in two placebo-controlled trials a low-dose blood-thinning tablet reduced clots but caused more bleeding. United States guidance says it may be offered; surveys in the Netherlands and China found most specialists do not use the score.","summary":"The score. The Khorana score was derived in 2,701 outpatients starting chemotherapy and validated in 1,365 more. It gives points for the site of the cancer (two for very high-risk sites, one for high-risk sites) and one point each for a platelet count of 350 x 10^9/L or more, haemoglobin below 100 g/L or use of an erythropoiesis-stimulating agent, a white cell count above 11 x 10^9/L, and a body mass index of 35 or more. Symptomatic clots over a median 2.5 months occurred in 0.8 and 0.3 per cent of the low-risk group and 7.1 and 6.7 per cent of the high-risk group in the two cohorts.\n\nThe trials. AVERT randomised 574 patients with a score of 2 or more starting chemotherapy to apixaban 2.5 mg twice daily or placebo: clots occurred in 4.2 per cent against 10.2 per cent (hazard ratio 0.41), and major bleeding in 3.5 per cent against 1.8 per cent (hazard ratio 2.00). CASSINI randomised 841 patients to rivaroxaban 10 mg daily or placebo: the primary endpoint at 180 days was 6.0 against 8.8 per cent (hazard ratio 0.66, P = 0.10), which was not statistically significant; during the period patients were actually taking the drug it was 2.6 against 6.4 per cent (hazard ratio 0.40), with major bleeding 2.0 against 1.0 per cent.\n\nThe guidance. The 2019 ASCO update, published in 2020, states that clinicians \"may offer thromboprophylaxis with apixaban, rivaroxaban, or LMWH to selected high-risk outpatients with cancer\", that thromboprophylaxis is not routinely recommended for all outpatients, and that patients should be periodically assessed for risk; the 2023 update revised the surgical and treatment recommendations.\n\nThe measured gap. In a 2025 Dutch survey of 38 medical oncologists treating pancreatic cancer, 63 per cent had never prescribed thromboprophylaxis to ambulatory patients on chemotherapy, 11 per cent used the Khorana score and 3 per cent always discussed clot risk with patients; the commonest reason given was the lack of a national guideline recommendation. In a 2025 survey of 235 physicians in Chinese tertiary hospitals treating advanced lung cancer, 57.8 per cent routinely used the score and 49.4 per cent said they were familiar with it.","asOf":"2026-10-20","links":[{"label":"Khorana et al., Development and validation of a predictive model for chemotherapy-associated thrombosis (Blood 2008)","url":"https://doi.org/10.1182/blood-2007-10-116327"},{"label":"Carrier et al., Apixaban to Prevent Venous Thromboembolism in Patients with Cancer: AVERT (N Engl J Med 2019)","url":"https://doi.org/10.1056/NEJMoa1814468"},{"label":"Khorana et al., Rivaroxaban for Thromboprophylaxis in High-Risk Ambulatory Patients with Cancer: CASSINI (N Engl J Med 2019)","url":"https://doi.org/10.1056/NEJMoa1814630"},{"label":"Key et al., Venous Thromboembolism Prophylaxis and Treatment in Patients With Cancer: ASCO Clinical Practice Guideline Update (J Clin Oncol 2020)","url":"https://doi.org/10.1200/JCO.19.01461"},{"label":"Key et al., Venous Thromboembolism Prophylaxis and Treatment in Patients With Cancer: ASCO Guideline Update (J Clin Oncol 2023)","url":"https://doi.org/10.1200/JCO.23.00294"},{"label":"Willems et al., Prevention of Venous Thromboembolism in Patients With Pancreatic Cancer: a nationwide survey (Cancer Med 2026)","url":"https://doi.org/10.1002/cam4.72306"},{"label":"Wang et al., Gaps Between Guidelines and Practice in VTE Prevention for Advanced NSCLC Outpatients: a nationwide cross-sectional study in China (Healthcare 2026)","url":"https://doi.org/10.3390/healthcare14070910"}],"tags":["protocol-upgrade","upgrade:proven-unevenly-used","evidence:moderate","precision"],"related":[],"cancers":["pancreatic","nsclc"],"sections":["supportive-care","chemotherapy"],"technologies":["cancer-associated-thrombosis"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["vte"],"trials":[],"people":[],"bottlenecks":["b-toxicity-qol","b-knowledge-diffusion"],"keyPapers":["paper-key-j-clin-oncol"],"journals":[],"dependsOn":[],"notes":[],"hypothesis":"Calculating the score automatically at the first chemotherapy prescription and presenting the option of prophylaxis with its bleeding risk to every patient scoring 2 or more increases informed prophylaxis decisions and lowers symptomatic clots in that group, without a net rise in major bleeding.","rationale":"The score uses numbers already in the record, so the only reason it is not calculated is that nobody is prompted to. The trials make this a preference-sensitive choice, fewer clots against more bleeding, which is a reason to put the choice in front of the patient rather than to make it silently either way.","test":"A stepped-wedge trial across chemotherapy units introducing an automatic score with a decision prompt, measuring the proportion of high-risk patients offered prophylaxis, symptomatic clots and major bleeding at six months.","maturity":"being-tested-at-scale","actor":"clinic","cost":"small","horizonYears":2},"route":"/ideas/idea-upgrade-clot-risk-score-and-preventive-anticoagulation/","neighbours":{"cancer":[{"id":"nsclc","kind":"cancer","name":"Non-small-cell lung cancer","route":"/cancers/nsclc/"},{"id":"pancreatic","kind":"cancer","name":"Pancreatic ductal adenocarcinoma","route":"/cancers/pancreatic/"}],"section":[{"id":"chemotherapy","kind":"section","name":"Chemotherapy","route":"/fronts/chemotherapy/"},{"id":"supportive-care","kind":"section","name":"Supportive Care & Survivorship","route":"/fronts/supportive-care/"}],"technology":[{"id":"cancer-associated-thrombosis","kind":"technology","name":"Cancer-associated thrombosis prevention and treatment","route":"/technologies/cancer-associated-thrombosis/"}],"term":[{"id":"vte","kind":"term","name":"Venous thromboembolism (VTE)","route":"/terms/vte/"}],"bottleneck":[{"id":"b-knowledge-diffusion","kind":"bottleneck","name":"Knowledge reaches practice too slowly","route":"/bottlenecks/b-knowledge-diffusion/"},{"id":"b-toxicity-qol","kind":"bottleneck","name":"Toxicity and quality of life are undervalued","route":"/bottlenecks/b-toxicity-qol/"}],"paper":[{"id":"paper-key-j-clin-oncol","kind":"paper","name":"Venous Thromboembolism Prophylaxis and Treatment in Patients With Cancer: ASCO Guideline Update","route":"/key-papers/paper-key-j-clin-oncol/"}]}}