SPN Malignancy Risk Calculator

SPN Malignancy Risk Calculator for Pulmonology. The displayed probability is a model estimate for an eligible nodule, not pathology or a surveillance, biopsy or resection instruction. Recent cancer, subsolid morphology and different detection settings can invalidate transfer of the original model.

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

The original Mayo SPN model applies a logistic transform to age, smoking, remote extrathoracic cancer, nodule diameter, spiculation and upper-lobe location. Diameter is in mm, not cm, and the model uses a remote-cancer definition rather than any malignancy.

When to use this calculator

Use only after a clinician determines that the nodule and patient resemble the intended population. The original study concerned radiographically identified 4-30 mm nodules; this is not a universal model for all CT findings, screening nodules, or recent cancer.

Inputs used

  • Age (completed years)
  • Current or former smoking
  • Extrathoracic cancer more than five years before nodule detection
  • Solitary pulmonary nodule diameter (mm)
  • Spiculation on imaging
  • Upper-lobe location
  • Original-model eligibility

Clinical interpretation

The displayed probability is a model estimate for an eligible nodule, not pathology or a surveillance, biopsy or resection instruction. Recent cancer, subsolid morphology and different detection settings can invalidate transfer of the original model.

Worked example

Fictional teaching case. Age (completed years): 68; Current or former smoking: Yes; Extrathoracic cancer more than five years before nodule detection: Yes; Solitary pulmonary nodule diameter (mm): 16; Spiculation on imaging: Yes; Upper-lobe location: Yes; Original-model eligibility: No cancer diagnosed within five years; indeterminate solitary nodule. Result: 86.116501 %. Mayo-model estimated malignancy probability. This estimate is not pathology and is not a biopsy, surveillance or resection recommendation. Check model applicability and compare with prior imaging.

Limitations and safety notes

The derivation used 4-30 mm indeterminate solitary nodules and excluded cancer within five years. Screening-detected, subsolid, multiple nodules and patients with recent cancer may need other pathways. Calibration is population dependent.

Frequently asked questions

What can change the meaning of this result?

The derivation used 4-30 mm indeterminate solitary nodules and excluded cancer within five years. Screening-detected, subsolid, multiple nodules and patients with recent cancer may need other pathways. Calibration is population dependent.

References

  • Original Swensen cohort and eligibility restrictions. https://pubmed.ncbi.nlm.nih.gov/9129544/
  • Primary model comparison reproduces the exact Mayo coefficients in Equation 2. https://www.nature.com/articles/s41467-025-65930-6

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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