Abstract
We studied the rate of incidental detection of lung carcinomas and its effect on long-term survival in a nationwide cohort of patients operated for nonsmall cell lung cancer (NSCLC). All patients operated for NSCLC in Iceland during 1991-2010 were included. Demographic and clinicopathological features were compared in patients diagnosed incidentally using chest radiography or computed tomography (CT), and in those with symptomatic presentation. Multivariate analysis was used to evaluate prognostic factors. Out of 508 patients, 174 (34%) were diagnosed incidentally; in 26% of cases by chest radiography and in 8% by CT. The CT-detected tumours were significantly smaller than symptomatic tumours, diagnosed at earlier TNM (tumour, node and metastasis) stages and more often of adenocarcinoma histology. 5-year cancer-specific survival for symptomatic versus incidentally diagnosed patients detected by chest radiography and CT was 41%, 57% and 68%, respectively (p=0.003). After adjusting for stage, the hazard ratio (HR) for NSCLC mortality was significantly lower for incidental diagnosis by CT (HR 0.55, 95% CI 0.31‒0.98; p=0.04) compared to incidental diagnosis by chest radiography (HR 0.95, 95% CI 0.70‒1.27; p=0.71) or symptomatic diagnosis (HR 1.0). One-third of surgically treated NSCLCs were detected incidentally, with an increasing rate of incidental CT diagnosis. NSCLC patients diagnosed incidentally by CT appear to have better survival than those diagnosed incidentally by chest radiography, and particularly those who present with symptoms.