Solitary Pulmonary Nodule (SPN) Malignancy Risk Score (Mayo Clinic Model)
SPN Malignancy Risk Calculator
years
mm
Current or Former Smoker
History of Extrathoracic Cancer (>5 years ago)
Spiculated Nodule
Upper Lobe Location
Malignancy Risk:–
%
–
–
Predicts malignancy risk in solitary lung nodules on chest x-ray.
When to Use
Patients with solitary lung nodule on chest x-ray. Do not use in patients with prior lung cancer diagnosis or with history of extrathoracic cancer diagnosed within 5 years of nodule presentation.
Formula
Probability of malignancy, % = 100 × e x / (1 + e x ) Probability of malignancy with FDG-PET, % = 100 / (1 + e -y ) where: x = (0.0391 × age, years) + (0.1274 × nodule diameter, mm) + (0.7917 × smoker) + (1.3388 × cancer) + (0.7838 × upper lobe) + (1.0407 × spiculation) - 6.8272, y = -4.739 + (3.691 × probability of malignancy*) + 2.322 (if faint uptake), or + 4.617 (if moderate uptake), or + 4.771 (if intense uptake), and other variables are as follows: Variable Points Current or former smoker No 0 Yes 1 Extrathoracic cancer diagnosis ≥5 years prior No 0 Yes 1 Upper lobe location of tumor No 0 Yes 1 Nodule spiculation No 0 Yes 1 *Note: expressed as a decimal, e.g. 0.12 for 12%.
Advice
One study ( Gould 2003 ) suggests watchful waiting only at very low post-test probabilities (<2%), biopsy at "lower" post-test probabilities (2% to 20%), and surgery at higher post-test probabilities (>70%).