Predictors of primary lung cancer in a solitary pulmonary lesion after a previous malignancy

Objective: A solitary pulmonary lesion in patients with a history of malignancy may be either primary lung cancer or a metastatic lung tumor or benign nodule. We retrospectively examined the preoperative predictive factors for determining the type of pathology. Methods: We used an exact logistic regression analysis to identify radiological and clinical predictors of primary lung cancer. The study included 187 patients who underwent pulmonary resection for a solitary pulmonary lesion and had received previous treatment for a malignancy. Results: There were 107 patients with primary lung cancer, 74 with metastatic lung tumors, and 6 with benign lesions. The previous malignancy included colorectal cancer in 71 patients. A disease-free interval exceeding 5 years and ground-glass opacity were found in 27.0% (20/74) and 1.4% (1/74) of metastatic lung tumors, respectively. Multivariate logistic regression analysis demonstrated that spiculation [adjusted odds ratio (a-OR), 1.74; 95% confidence interval (CI), 1.09–2.86], pleural indentation (a-OR 1.99, 95% CI 1.24–3.29), and ground-glass opacity (a-OR 5.28, 95% CI 2.61–13.1) on high-resolution computed tomography, maximum standardized uptake value (a-OR 1.14, 95% CI 1.02–1.29), current and former smokers (a-OR 1.96, 95% CI 1.21–3.30), and previous malignancy other than colorectal cancer (a-OR 2.02, 95% CI 1.26–3.37) were associated with primary lung cancer. Conclusions: A combination of radiological findings, smoking history, and type of previous malignancy can improve the ability to predict primary lung cancer in the presence of a solitary pulmonary lesion that appears after previous treatment for a malignancy.