Lung Nodule Growth Rate Calculator
Estimate malignancy probability for pulmonary nodules using the Brock University prediction model.
Pulmonary Nodule Malignancy Risk
Incidental or screening-detected lung nodules are common on chest CT. The Brock University prediction model estimates the probability that a nodule represents lung cancer within 2–4 years of follow-up, combining patient demographics, emphysema, family history, and nodule morphology. To assess overall spirometry volumes, use the Lung Capacity Calculator.
The Brock University Model
The model computes a log-odds score from age, sex, emphysema, family history of lung cancer, spiculation, upper-lobe location, nodule count, maximum nodule diameter in millimeters, and nodule type (nonsolid, partially solid, or solid). The log-odds converts to a cancer probability percentage using the logistic function.
Interpreting Results
Probabilities below 5% are generally considered low risk and may support routine surveillance intervals. Values between 5% and 15% suggest moderate risk warranting closer follow-up. Probabilities at or above 15% typically prompt specialist referral and further diagnostic evaluation. These thresholds are guides; management follows current guideline recommendations and full clinical context.
Frequently Asked Questions
What is the Brock model used for?
The Brock University equation predicts malignancy risk for pulmonary nodules found on low-dose screening CT or diagnostic imaging. It was validated in large screening cohorts and supports shared decision-making about follow-up intervals.
What nodule size should I enter?
Enter the maximum diameter of the largest nodule in millimeters (mm), as reported on the radiology report. The model uses size/10 raised to the power −0.5 in the equation.
What is spiculation?
Spiculation refers to irregular, spiky or starburst-like margins of a nodule on CT. Spiculated borders are associated with higher malignancy risk and add a positive coefficient in the Brock model.
How do nodule types affect risk?
Solid nodules carry a baseline coefficient of zero. Partially solid nodules add positive risk, while nonsolid or ground-glass nodules subtract from the log-odds, reflecting their generally lower short-term malignancy rates.
Does this calculator measure nodule growth rate?
Despite its name, this tool estimates malignancy probability using the Brock model rather than computing volumetric doubling time. Growth rate assessment requires serial imaging comparing nodule size over time.
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