Estimate Malignancy Risk (Mayo Clinic Model)
Use this tool to estimate the probability that a solitary pulmonary nodule is malignant. Enter the patient and nodule features below.
Educational use only. This estimate does not replace radiology review, guideline-based follow-up, or specialist judgment.
What this pulmonary nodule risk calculator does
A pulmonary nodule is a small round or oval opacity in the lung seen on imaging, usually CT. Most nodules are benign, but some represent early lung cancer. This calculator helps estimate the likelihood of malignancy using a well-known clinical prediction equation (the Mayo Clinic model).
The main goal is to support clinical decision-making by combining key risk factors into a single probability. It can be useful for discussing next steps, such as surveillance CT, PET-CT, biopsy, or referral to a multidisciplinary lung nodule clinic.
How the risk estimate is calculated
The model uses six features:
- Age
- Nodule diameter
- Smoking history
- Prior extrathoracic cancer (more than 5 years earlier)
- Upper lobe location
- Spiculated nodule margin
These variables are entered into a logistic equation that returns a probability from 0% to 100%. Higher values suggest higher suspicion for malignancy.
How to interpret the result
Low risk
Low-risk nodules are often managed with serial imaging based on size and morphology. Follow-up intervals are usually determined by accepted guidelines and clinical context.
Intermediate risk
Intermediate-risk nodules often require additional risk stratification. PET-CT, volume-doubling assessment, or tissue sampling may be considered depending on patient factors and imaging details.
High risk
High-risk nodules may warrant expedited specialist evaluation and definitive diagnostic workup. In selected patients, treatment planning may proceed quickly after multidisciplinary discussion.
Important limitations
- This tool is not a diagnosis.
- Risk models perform best when used in the populations they were developed for.
- Other CT findings (calcification pattern, growth rate, subsolid features, cavitation) are not fully captured here.
- Clinical factors such as family history, occupational exposures, and regional infection prevalence can change pretest probability.
- Always interpret the score with formal radiology and clinician review.
When to seek urgent medical review
If a patient has concerning symptoms such as persistent hemoptysis, unexplained weight loss, progressive dyspnea, chest pain, or rapidly worsening imaging findings, urgent medical assessment is appropriate regardless of calculator output.
Practical workflow for clinicians
- Confirm nodule characteristics on a high-quality CT report.
- Estimate risk using this calculator.
- Classify risk and compare with guideline pathways (e.g., Fleischner or NCCN context as applicable).
- Discuss options with the patient, including surveillance versus further testing.
- Document shared decision-making and follow-up plan.
Bottom line
A pulmonary nodule risk calculator is a useful decision support tool. It works best when paired with expert imaging interpretation, patient-specific clinical judgment, and evidence-based follow-up protocols.