nodule on lung CT and risk of lung cancer

Last edited 05/2018 and last reviewed 01/2021

Nodule on lung CT and risk of lung cancer

Main challenge in CT screening for lung cancer is the high prevalence of pulmonary nodules and the relatively low incidence of lung cancer

• a prespecified analysis was undertaken (1), using data from the NELSON CT screening trial
  • aimed to quantify how nodule diameter, volume, and volume doubling time affect the probability of developing lung cancer within 2 years of a CT scan, and to propose and evaluate thresholds for management protocols

    7,155 adults (median age 58 years, 84% men) who were current or former smokers (cessation <= 10 years) from NELSON trial and who were randomized to LDCT screening were assessed

    • all had >= 1 screening within 2 years of baseline screening
    • volume and diameter of solid nodules determined by automated software and by manual estimation for non-solid nodules
    • participants in the NELSON trial were those aged 50-75 years, who have smoked 15 cigarettes or more per day for more than 25 years, or ten cigarettes or more for more than 30 years and were still smoking, or had stopped smoking less than 10 years ago
    • participants were randomly assigned to low-dose CT screening at increasing intervals, or no screening
    • calculated lung cancer probabilities, stratified by nodule diameter, volume, and volume doubling time and did logistic regression analysis using diameter, volume, volume doubling time, and multinodularity as potential predictor variables
    • lung cancer diagnosis based on Dutch national cancer registry records

Rates of lung cancer within 2 years (statistical comparison vs. no nodules)

• maximum transverse diameter of lung nodule
  • 0.4% in patients with no nodules
  • 0.4% in patients with diameter < 5 mm (not significant)
  • 1.3% in patients with diameter 5-10 mm (p < 0.0001)
  • 15.2% in patients with diameter >= 10 mm (p < 0.0001)

Authors' interpretation of this study:

• small nodules (those with a volume <100 mm^3 or diameter <5 mm) are not predictive for lung cancer
• immediate diagnostic evaluation is necessary for large nodules (>=300 mm^3 or >=10 mm)
• volume doubling time assessment is advocated only for intermediate-sized nodules (with a volume ranging between 100-300 mm^3 or diameter of 5-10 mm).

Contributor (May 10th 2018):

• Dr Judith Drought
  • Respiratory Consultant, University Hospital Coventry & Warwickshire, Walsgrave, Coventry Clifford Bridge Rd, Coventry CV2 2DX

Reference

• Lancet Oncol 2014 Nov;15(12):1332