Khorana Score Calculator
Five variables estimate VTE risk in ambulatory cancer patients starting chemotherapy — the score behind the AVERT and CASSINI prophylaxis trials. Plus the vascular-neurology corner: malignancy-associated hypercoagulability causes strokes, not just DVTs.
Reviewed by Zaka Ahmed, MD Clinical reference · 3 min read
Khorana Score
Score before starting systemic chemotherapy in an ambulatory cancer patient. Total 0–6+.
Score every item to see the risk band and prophylaxis implication.
Educational tool only. Thromboprophylaxis in cancer is an oncology decision balancing bleeding risk, drug interactions, and prognosis; the trial thresholds summarized here inform, not replace, that decision or clinical judgment.
Clinical notes & interpretation Scoring guidance, pitfalls, FAQs, and references
The score that made ambulatory prophylaxis a real question
Khorana's model turned "cancer causes clots" into a usable stratification: site of malignancy plus four routine labs and BMI. AVERT (apixaban 2.5 mg BID) and CASSINI (rivaroxaban 10 mg daily) then tested prophylaxis in patients scoring ≥2 and found meaningful VTE reduction at acceptable bleeding cost, which is why modern guidelines allow offering DOAC prophylaxis at that threshold. The score's known blind spots: it was built around chemotherapy initiation (performance in immunotherapy and targeted-agent eras is debated), and some high-thrombotic cancers — notably primary brain tumors and myeloma — sit awkwardly in it.
Cancer, clots, and the brain
The same hypercoagulability drives arterial events. Cancer-associated ischemic stroke is a recognized phenotype worth suspecting when you see multi-territory embolic-appearing infarcts with no cardiac source, markedly elevated d-dimer, unexplained weight loss, or a "cryptogenic" stroke in a patient with known active malignancy — nonbacterial thrombotic endocarditis and mucin-producing adenocarcinomas (the same stomach and pancreas that top this score) are the classic culprits. The management follows the mechanism: workup includes TEE and malignancy evaluation when the pattern suggests it, and anticoagulation — historically LMWH, increasingly DOACs — rather than antiplatelets is usually the secondary-prevention choice once cancer-associated thrombosis is the working diagnosis. A patient whose Khorana logic says "very high risk" is the same patient whose cryptogenic stroke should not be closed out as ESUS without a cancer thought.
Frequently asked questions.
What Khorana score triggers prophylaxis?
Trials (AVERT, CASSINI) enrolled at ≥2, and guidelines permit offering apixaban 2.5 mg BID or rivaroxaban 10 mg daily at that threshold in ambulatory patients starting chemotherapy, when bleeding risk is acceptable.
Does the score apply to hospitalized or surgical cancer patients?
No — those settings have their own prophylaxis standards (hospitalized medical patients and perioperative pathways). Khorana is for ambulatory patients starting systemic therapy.
Why do stomach and pancreas score double?
They are the most thrombogenic common malignancies — mucinous adenocarcinomas activate coagulation directly — which is also why they headline nonbacterial thrombotic endocarditis and cancer-associated stroke.
References.
- Khorana AA, Kuderer NM, Culakova E, Lyman GH, Francis CW. Development and validation of a predictive model for chemotherapy-associated thrombosis. Blood. 2008;111(10):4902–4907. PubMed
- Carrier M, Abou-Nassar K, Mallick R, et al. Apixaban to prevent venous thromboembolism in patients with cancer (AVERT). N Engl J Med. 2019;380(8):711–719. PubMed
- Khorana AA, Soff GA, Kakkar AK, et al. Rivaroxaban for thromboprophylaxis in high-risk ambulatory patients with cancer (CASSINI). N Engl J Med. 2019;380(8):720–728. PubMed
- Navi BB, Iadecola C. Ischemic stroke in cancer patients: a review of an underappreciated pathology. Ann Neurol. 2018;83(5):873–883. PubMed