Coexisting pulmonary nodules in operable lung cancer: prevalence and probability of malignancy.

Introduction: Coexistence of pulmonary nodules in operable non small cell lung cancer (NSCLC) may influence the therapeutic indication. The aim of this study was to evaluate prospectively the prevalence and the probability of malignancy of pulmonary nodules in operable lung cancer.

Methods: From a prospective database, all surgically treated patients diagnosed with NSCLC from 1998 to 2003 were retrospectively reviewed. Patients presenting pulmonary nodule(s) were identified.

Results: Two hundred thirty nine patients had a complete resection for a NSCLC and 56 patients (24%) presented altogether 88 nodules on thoracic CT. Twenty-four of these nodules (27%) were malignant, 28 (32%) benign and 36 (41%) of undetermined nature. Five factors associated with nodule's malignancy were identified: tumour histology (non-squamous (non-SCC) 44% vs. SCC 7%, p=0.001), localization of the nodules in an upper lobe (vs. other lobe, p=0.004), co localization in the same lobe as the NSCLC (vs. another lobe, p=0.03), nodule size (p=0.05) and shape (speculated vs. non spiculated, p=0.02). From these factors, a probability score was assessed with a malignancy rate in SCC of 0% in nodules presenting ≤ 1 feature, 33% with 2 features and 100% with ≥ 3 features and in non-SCC of 40% with 1 feature, 82% with 2 features and 100% with 3 ≥ features.

Conclusion: Diagnosis of satellite nodules associated with early stage NSCLC is common. We developed a predictive score to estimate the probability of malignancy which may be a precious aid in the management of pulmonary nodules associated to a NSCLC.