Also known as Khorana Score, Khorana risk score
Symptomatic VTE observed in outpatients starting a new chemotherapy regimen, by score.
Clinically reviewed byJennifer J. Wu, MDNot an endorsement of any individual result, and no substitute for the treating clinician’s judgement.
Reviewed Nov 7, 2026Version 1.0.0Next review Nov 7, 2027
Applies to / doesn’t apply to6
Applies to: Adults with histologically confirmed cancer, treated as outpatients, at the start of a new chemotherapy regimen. Prior chemotherapy was allowed.
- Inpatients.
- Patients not starting a new chemotherapy regimen, including those on continuous single-agent chemotherapy.
- Acute leukaemia, or after stem-cell transplant.
- Pregnancy or lactation.
- Under 18.
- As a test for a suspected current clot.
Primary site of the cancer being treated. Stomach (including gastro-oesophageal junction) or pancreas scores 2; lung, lymphoma, gynecologic, bladder (including upper-tract urothelial) or testicular scores 1. Any other site scores 0, including breast, colorectal, prostate, head and neck, brain, kidney, myeloma, oesophageal, cholangiocarcinoma and ampullary cancer.
Pre-chemotherapy platelet count of 350 × 10⁹/L (350,000/µL) or more.
Baseline haemoglobin below 10 g/dL (100 g/L), or use of a red-cell growth factor (erythropoiesis-stimulating agent). Counts once if either applies. In the original study, growth-factor use was recorded up to the start of the second cycle.
Pre-chemotherapy leukocyte count of more than 11 × 10⁹/L (11,000/µL). A count of exactly 11 × 10⁹/L is No.
Body-mass index of 35 kg/m² or more.
What this score estimates
The Khorana score adds up five factors (cancer site, platelet count, haemoglobin or red-cell growth-factor use, leukocyte count and body-mass index) and places an adult outpatient starting a new chemotherapy regimen in one of three risk groups for symptomatic venous thromboembolism.
Pearls & pitfalls
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- Discrimination is modest: a c-statistic of 0.7 in the original cohorts and 0.60 in 40,218 patients starting chemotherapy in Denmark.
- Most clots occur below the high-risk band: in the derivation cohort, 40% of patients who developed VTE had a score of 3 or more.
- The original study included too few patients with brain or renal cancer or myeloma; this calculator scores them as other sites (0 points), as the original scoring table does. The authors suggested the high-risk-site score may be extended to brain tumours, and a later trial scored brain, myeloma and kidney cancer.
- The original score does not address two primary cancers; this calculator scores one site, the primary site of the cancer being treated.
- A meta-analysis found the score less informative in lung cancer and haematological malignancies.
- Clots were diagnosed by treating clinicians and not independently adjudicated, in a 2002–2005 registry designed to study febrile neutropenia; the validation cohort was a random split of the same registry.
Not captured by the score:
- Prior VTE, central venous catheters, current anticoagulant or antiplatelet use, specific chemotherapy agents, cancer stage, performance status, recent surgery, immobility and D-dimer.
What the guidelines say
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The 2021 American Society of Hematology guidelines state that classifying ambulatory patients with cancer as low, intermediate or high risk for VTE should be based on a validated risk-assessment tool, naming the Khorana score, complemented by clinical judgement and experience.
View guideline source ↗The 2022 international (ITAC) guidelines identify ambulatory patients receiving systemic anticancer therapy at intermediate-to-high risk of VTE by a Khorana score of 2 or more, a lower threshold than this paper's high-risk band of 3 or more.
View guideline source ↗The 2020 ASCO guideline, kept in its 2023 update, describes outpatients with a Khorana score of 2 or more before starting a new systemic chemotherapy regimen as high risk, a lower threshold than this paper's high-risk band of 3 or more.
View guideline source ↗ISTH guidance from 2019 notes that the two main trials in this population enrolled patients with a Khorana score of 2 or more.
View guideline source ↗One of those trials (AVERT) used a modified score that also gave points for brain tumours, myeloma and kidney cancer; this calculator uses the original scoring table.
View guideline source ↗Guideline positions are stated as published. Curie.MD Calc does not publish treatment direction.
Where this comes from
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How it’s scored
What was observed
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. View source ↗
- Overvad TF, Ording AG, Nielsen PB, et al. Validation of the Khorana score for predicting venous thromboembolism in 40 218 patients with cancer initiating chemotherapy. Blood Adv. 2022;6(10):2967-2976. View source ↗
- Mulder FI, Candeloro M, Kamphuisen PW, et al. The Khorana score for prediction of venous thromboembolism in cancer patients: a systematic review and meta-analysis. Haematologica. 2019;104(6):1277-1287. View source ↗
- Lyman GH, Carrier M, Ay C, et al. American Society of Hematology 2021 guidelines for management of venous thromboembolism: prevention and treatment in patients with cancer. Blood Adv. 2021;5(4):927-974. View source ↗
- Farge D, Frere C, Connors JM, et al. 2022 international clinical practice guidelines for the treatment and prophylaxis of venous thromboembolism in patients with cancer, including patients with COVID-19. Lancet Oncol. 2022;23(7):e334-e347. View source ↗
- Key NM, Khorana AA, Kuderer NM, et al. Venous thromboembolism prophylaxis and treatment in patients with cancer: ASCO clinical practice guideline update. J Clin Oncol. 2020;38(5):496-520. View source ↗
- Wang TF, Zwicker JI, Ay C, et al. The use of direct oral anticoagulants for primary thromboprophylaxis in ambulatory cancer patients: guidance from the SSC of the ISTH. J Thromb Haemost. 2019;17(10):1772-1778. View source ↗