Factors influencing the prevalence of pulmonary nodules in lung cancer screening trials: re-evaluation of a CT study

Abstract

Numerous false positive findings are a problem in computed tomography based lung cancer screening trials. The potential patient-related variables that could predict the existence of such lung nodules were studied. 526 construction workers (age 38 - 81 yrs.) previously screened with spiral computed tomography were evaluated. Background features (age, body mass index, stature, sex, C-reactive protein, erythrocyte sedimentation rate, asbestos exposure and smoking history), reported symptoms (general condition, cough, mucous production, dyspnoea, chest pain) and findings in high resolution CT were related to the existence of nodules with logistic regression. There were 107 patients with one or more nodules recorded at least by two of the three observers. Advancing age (OR = 1.042/year, 95% CI = 1.000 - 1.085, p = 0.048) and dyspnoea symptom (p = 0.014) were positively associated with the existence of nodules, while smoking, asbestos exposure history and other studied parameters were not. Nodules ≤ 5 mm (50 patients) were inversely associated with the maximal thickness of pleural plaques (OR = 0.384, 95% CI = 0.169 - 0.873, p = 0.022). No variables helpful to sample subjects for lung cancer screening studies to reduce the number of false positive findings were found. Poor inspiration or associated pathology such as thick pleura may hamper nodule detection. Further studies should focus especially on the possible effect of computer tomography technology on finding nodules.