Khorana Score Calculator (Cancer-Associated VTE Risk)
Calculate the Khorana score for venous thromboembolism risk in ambulatory patients starting chemotherapy — cancer site, platelets, hemoglobin, white cells and BMI — with risk group and ASCO prophylaxis guidance.
How it works
Khorana = cancer site (stomach or pancreas 2; lung, lymphoma, gynecologic, bladder or testicular 1; other 0) + platelets ≥ 350 × 10⁹/L (1) + Hb < 10 g/dL or ESA use (1) + WBC > 11 × 10⁹/L (1) + BMI ≥ 35 (1). Low risk 0 · intermediate 1–2 · high ≥ 3.
The Khorana score (Khorana et al., Blood 2008) predicts symptomatic venous thromboembolism in outpatients starting chemotherapy, using blood counts taken before treatment. In the derivation and validation cohorts the VTE rate over about 2.5 months was 0.3–0.8% at a score of 0, 1.8–2% at 1–2 and 6.7–7.1% at 3 or more. ASCO guidelines (2019, updated 2023) say high-risk outpatients with a Khorana score of 2 or more may be offered prophylaxis with apixaban, rivaroxaban or low-molecular-weight heparin, provided there are no significant bleeding risks or drug interactions.
Worked example
A patient with lung cancer (1) and a pre-chemotherapy platelet count of 410 × 10⁹/L (1), with normal hemoglobin, white cells and BMI, scores Khorana = 2 / 6 — intermediate risk (1.8–2% VTE in about 2.5 months); under ASCO guidance thromboprophylaxis may be offered if bleeding risk is acceptable.
Sources: Khorana AA et al. Development and validation of a predictive model for chemotherapy-associated thrombosis. Blood 2008 · Key NS et al. Venous thromboembolism prophylaxis and treatment in patients with cancer: ASCO guideline update. J Clin Oncol 2023
Frequently asked questions
What Khorana score is high risk?
In the original study 3 or more was high risk (about 7% VTE in 2.5 months). ASCO uses a score of 2 or more as the threshold for offering primary thromboprophylaxis to outpatients on chemotherapy.
Why do stomach and pancreatic cancer score 2?
They carried the highest rates of venous thromboembolism in the derivation cohort; lung, lymphoma, gynecologic, bladder and testicular cancers were high but lower, scoring 1. Brain tumours and myeloma are high risk but were not part of the original score.
Which blood results should I use?
The counts taken before the first cycle of chemotherapy, as in the original study.
Does a low score mean no clots?
No — VTE can still occur. Watch for leg swelling, chest pain or breathlessness and seek urgent care if they appear.
Related calculators
Clinical decision tool for education and for use by trained clinicians alongside clinical judgement — not a diagnosis and not a substitute for medical assessment. Scores validated in specific populations may not apply to every patient.